Get Uptime of remote computers

Get-MyUptime.ps1

# Jeff Hicks
# http://www.petri.com/creating-advance-functions-powershell.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+Petri+%28Petri+IT+Knowledgebase%29

Function Get-MyUptime {
[cmdletbinding()]
Param(
[Parameter(Position=0,ValueFromPipeline,ValueFromPipelineByPropertyName)]
[ValidateNotNullorEmpty()]
[Alias("cn","host")]
[string[]]$Computername = $env:Computername
)

Begin {
    Write-Verbose -Message "Starting $($MyInvocation.Mycommand)"  
} #begin

Process {
    Foreach ($computer in $computername) {
        Write-Verbose "Getting uptime from $($computer.toupper())"
        Try {
            $Reboot = Get-CimInstance Win32_OperatingSystem -ComputerName $computer -ErrorAction Stop  | Select-Object CSName,LastBootUpTime
        }
        Catch {
           Write-Error $_
        }

        if ($Reboot) {
            Write-Verbose "Calculating timespan from $($reboot.LastBootUpTime)"  
            #create a timespan object and pipe to Select-Object
            New-TimeSpan -Start $reboot.LastBootUpTime -End (Get-Date) | 
            Select-Object @{Name = "Computername"; Expression = {$Reboot.CSName}},
            @{Name = "LastRebootTime"; Expression = {$Reboot.LastBootUpTime}},Days,Hours,Minutes,Seconds 

            #reset variable so it doesn't accidentally get re-used, especially when using the ISE
            Remove-Variable -Name Reboot
        }
    } #foreach
} #process

End {
    Write-Verbose -Message "Ending $($MyInvocation.Mycommand)"
} #end

} #end function