Creating a GUID has always been possible with PowerShell – you just had to drop into .NET
With the latest WMF 5.0 preview life gets easier:
£> Get-Command New-Guid -Syntax
The New-Guid cmdlet happily creates a GUID for you – and you don’t have to remember the >NET syntax.
If you want the GUID in a variable as a string
£> $guid = New-Guid | select -ExpandProperty Guid