Check-WindowsPreview.ps1

# Modified version of http://poshcode.org/5474 by @sorlov
function DoSomething {}

function Check-WindowsPreview
{
    PARAM(
        [int]$Sleep=10,
        [switch]$WaitForIt
    )

    BEGIN
    {	
        do
        {
            try
            {
                $startTime = Get-Date
                $output = Invoke-WebRequest -Method Get -Uri "http://preview.windows.com" -UserAgent "Powershell Script" -UseBasicParsing
                $endTime = Get-Date

                if ($output.Content -match "so please check back soon")
                {
                    $Props = [ordered]@{
                        Released = "NotYet"
                        StartTime = $startTime
                        EndTime = $endTime
                        Duration = ($endTime - $startTime).TotalSeconds
                    }
                    New-Object -TypeName PSObject -Property $Props
                }
                else
                {
                    $Props = [ordered]@{
                        Released = "Yes"
                        StartTime = $startTime
                        EndTime = $endTime
                        Duration = ($endTime - $startTime).TotalSeconds
                    }
                    New-Object -TypeName PSObject -Property $Props
                    $WaitForIt = $false
                    DoSomething
                }
            }
            catch
            {
                $Props = [ordered]@{
                    Released = "Unknown: $($_.Exception.Message)"
                    StartTime = $startTime
                    EndTime = $endTime
                    Duration = ($endTime - $startTime).TotalSeconds
                }
                New-Object -TypeName PSObject -Property $Props
            }

            if ($WaitForIt) { Start-Sleep -Seconds $Sleep }
        }
        while ($WaitForIt)
    }
}