While working with my team we discovered that we have an app or two that will fail if a pending reboot is detected...real pain right. I thought does this tool also check for that? Nope it does not. Well I was able to add an extension for checking pending reboots for remote machines (from Microsoft) and modified it to only use the local system. added it as a custom extension and viola!!! I now can check for pending restarts in the toolset and tell the script to act accordingly.

Here is how I check for and then prompt for a restart if needed and below that is the function, with only a couple mods to make it work for local only.

$isPending = Get-PendingReboot | select RebootPending
If($isPending.RebootPending -eq $True){

Show-InstallationRestartPrompt -CountdownSeconds 180 -CountdownNoHideSeconds 60
Exit-script 1618

}

*=============================================

Check for pending restart

*=============================================

Function Get-PendingReboot{
<#
.SYNOPSIS
Gets the pending reboot status on a local or remote computer.

.DESCRIPTION

This function will query the registry on a local or remote computer and determine if the
system is pending a reboot, from either Microsoft Patching or a Software Installation.
For Windows 2008+ the function will query the CBS registry key as another factor in determining
pending reboot state. "PendingFileRenameOperations" and "Auto Update\RebootRequired" are observed
as being consistant across Windows Server 2003 & 2008.

CBServicing = Component Based Servicing (Windows 2008)
WindowsUpdate = Windows Update / Auto Update (Windows 2003 / 2008)
CCMClientSDK = SCCM 2012 Clients only (DetermineIfRebootPending method) otherwise $null value
PendFileRename = PendingFileRenameOperations (Windows 2003 / 2008)

.PARAMETER ComputerName
A single Computer or an array of computer names. The default is localhost ($env:COMPUTERNAME).

.PARAMETER ErrorLog
A single path to send error data to a log file.

.EXAMPLE
PS C:> Get-PendingReboot -ComputerName (Get-Content C:\ServerList.txt) | Format-Table -AutoSize

Computer CBServicing WindowsUpdate CCMClientSDK PendFileRename PendFileRenVal RebootPending

---

DC01 False False False False
DC02 False False False False
FS01 False False False False

This example will capture the contents of C:\ServerList.txt and query the pending reboot
information from the systems contained in the file and display the output in a table. The
null values are by design, since these systems do not have the SCCM 2012 client installed,
nor was the PendingFileRenameOperations value populated.

.EXAMPLE
PS C:> Get-PendingReboot

Computer : WKS01
CBServicing : False
WindowsUpdate : True
CCMClient : False
PendFileRename : False
PendFileRenVal :
RebootPending : True

This example will query the local machine for pending reboot information.

.EXAMPLE
PS C:> $Servers = Get-Content C:\Servers.txt
PS C:> Get-PendingReboot -Computer $Servers | Export-Csv C:\PendingRebootReport.csv -NoTypeInformation

This example will create a report that contains pending reboot information.

.LINK
Component-Based Servicing:
http://technet.microsoft.com/en-us/library/cc756291(v=WS.10).aspx

PendingFileRename/Auto Update:
http://support.microsoft.com/kb/2723674
http://technet.microsoft.com/en-us/library/cc960241.aspx
http://blogs.msdn.com/b/hansr/archive/2006/02/17/patchreboot.aspx

SCCM 2012/CCM_ClientSDK:
http://msdn.microsoft.com/en-us/library/jj902723.aspx

.NOTES
Author: Brian Wilhite
Email: bwilhite1@carolina.rr.com Date: 08/29/2012
PSVer: 2.0/3.0
Updated: 05/30/2013
UpdNote: Added CCMClient property - Used with SCCM 2012 Clients only
Added ValueFromPipelineByPropertyName=$true to the ComputerName Parameter
Removed $Data variable from the PSObject - it is not needed
Bug with the way CCMClientSDK returned null value if it was false
Removed unneeded variables
Added PendFileRenVal - Contents of the PendingFileRenameOperations Reg Entry

>

[CmdletBinding()]
param(
[Parameter(Position=0,ValueFromPipeline=$true,ValueFromPipelineByPropertyName=$true)]
[Alias("CN","Computer")]
[String[]]$ComputerName="$env:COMPUTERNAME",
[String]$ErrorLog
)

Begin{

# Adjusting ErrorActionPreference to stop on all errors, since using [Microsoft.Win32.RegistryKey]
# does not have a native ErrorAction Parameter, this may need to be changed if used within another
# function.
$TempErrAct = $ErrorActionPreference
$ErrorActionPreference = "Stop"
}#End Begin Script Block

Process{

#Foreach ($Computer in $ComputerName){
    Try{
        # Setting pending values to false to cut down on the number of else statements
        $PendFileRename,$Pending,$SCCM = $false,$false,$false

        # Setting CBSRebootPend to null since not all versions of Windows has this value
        $CBSRebootPend = $null

        # Querying WMI for build version
        $WMI_OS = Get-WmiObject -Class Win32_OperatingSystem -Property BuildNumber, CSName -ComputerName $env:COMPUTERNAME

        # Making registry connection to the local/remote computer
        $RegCon = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey([Microsoft.Win32.RegistryHive]"LocalMachine",$env:COMPUTERNAME)

        # If Vista/2008 & Above query the CBS Reg Key
        If ($WMI_OS.BuildNumber -ge 6001){
            $RegSubKeysCBS = $RegCon.OpenSubKey("SOFTWARE\Microsoft\Windows\CurrentVersion\Component Based Servicing\").GetSubKeyNames()
            $CBSRebootPend = $RegSubKeysCBS -contains "RebootPending"
            }#End If ($WMI_OS.BuildNumber -ge 6001)

        # Query WUAU from the registry
        $RegWUAU = $RegCon.OpenSubKey("SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update\")
        $RegWUAURebootReq = $RegWUAU.GetSubKeyNames()
        $WUAURebootReq = $RegWUAURebootReq -contains "RebootRequired"

        # Query PendingFileRenameOperations from the registry
        $RegSubKeySM = $RegCon.OpenSubKey("SYSTEM\CurrentControlSet\Control\Session Manager\")
        $RegValuePFRO = $RegSubKeySM.GetValue("PendingFileRenameOperations",$null)

        # Closing registry connection
        $RegCon.Close()

        # If PendingFileRenameOperations has a value set $RegValuePFRO variable to $true
        If ($RegValuePFRO){$PendFileRename = $true}#End If ($RegValuePFRO)

        # Determine SCCM 2012 Client Reboot Pending Status
        # To avoid nested 'if' statements and unneeded WMI calls to determine if the CCM_ClientUtilities class exist, setting EA = 0
        $CCMClientSDK = $null
        $CCMSplat = @{
            NameSpace='ROOT\ccm\ClientSDK'
            Class='CCM_ClientUtilities'
            Name='DetermineIfRebootPending'
            ComputerName=$env:COMPUTERNAME
            ErrorAction='SilentlyContinue'
            }
        $CCMClientSDK = Invoke-WmiMethod @CCMSplat
        If ($CCMClientSDK){
                If ($CCMClientSDK.ReturnValue -ne 0){Write-Warning "Error: Determine IfRebootPending returned error code $($CCMClientSDK.ReturnValue)"}#End If ($CCMClientSDK -and $CCMClientSDK.ReturnValue -ne 0)
                If ($CCMClientSDK.IsHardRebootPending -or $CCMClientSDK.RebootPending){$SCCM = $true}#End If ($CCMClientSDK.IsHardRebootPending -or $CCMClientSDK.RebootPending)
            }#End If ($CCMClientSDK)
        Else{
            $SCCM = $null
            }                        

        # If any of the variables are true, set $Pending variable to $true
        If ($CBSRebootPend -or $WUAURebootReq -or $SCCM -or $PendFileRename){$Pending = $true}#End If ($CBS -or $WUAU -or $PendFileRename)

        # Creating Custom PSObject and Select-Object Splat
        $SelectSplat = @{
            Property=('Computer','CBServicing','WindowsUpdate','CCMClientSDK','PendFileRename','PendFileRenVal','RebootPending')
            }
        New-Object -TypeName PSObject -Property @{
            Computer=$WMI_OS.CSName
            CBServicing=$CBSRebootPend
            WindowsUpdate=$WUAURebootReq
            CCMClientSDK=$SCCM
            PendFileRename=$PendFileRename
            PendFileRenVal=$RegValuePFRO
            RebootPending=$Pending
            } | Select-Object @SelectSplat
    }#End Try
    Catch{
        Write-Warning "$Computer`: $_"
        # If $ErrorLog, log the file to a user specified location/path
        If ($ErrorLog){Out-File -InputObject "$env:COMPUTERNAME`,$_" -FilePath $ErrorLog -Append}#End If ($ErrorLog)              
    }#End Catch
#}#End Foreach ($Computer in $ComputerName)      

}#End Process

End{

# Resetting ErrorActionPref
$ErrorActionPreference = $TempErrAct
}#End End

}#End Function