PowerShell–Good Scripts guide
Ed Wilson, the Microsoft Scripting Guy, wrote recently http://blogs.technet.com/b/heyscriptingguy/archive/2012/03/08/2012-scripting-games-judging-criteria-revealed.aspx
about the judging for the 2012 games.
At the top of that post there is a section labelled General criteria for good Windows PowerShell scripts.
I would strongly recommend everyone who is working with PowerShell, whether you intend to enter the games or not, to read that section and apply it to every script you produce.
The advice doesn’t get better than that!