With this line, you always get back the process object representing the current PowerShell host:
PS> [System.Diagnostics.Process]::GetCurrentProcess()
This is the equivalent to:
PS> Get-Process -ID $PID
Either way, the process object returned can provide useful information like the host that runs your script, or the total time the process has been running:
PS> [System.Diagnostics.Process]::GetCurrentProcess().Description Windows PowerShell ISE PS> (Get-Process -ID $PID).Description Windows PowerShell ISE