Background Runspace

$hashUI = [hashtable]::Synchronized(@{})

$backgroundRS = [runspacefactory]::CreateRunspace()
$backgroundRS.ApartmentState = "STA"
$backgroundRS.ThreadOptions = "ReuseThread"
$backgroundRS.Open()
$backgroundRS.SessionStateProxy.SetVariable("hashUI", $hashUI)

$hashUI.BackgroundJobInfo = [powershell]::Create().AddScript({
    while ($true) {
        # ... do something periodically

        Start-Sleep -Seconds 60
    }
})
$hashUI.BackgroundJobInfo.Runspace = $backgroundRS
$hashUI.BackgroundJob = $hashUI.BackgroundJobInfo.BeginInvoke()