Below is a link to a presentation by Adam Edwards from the recent #chefconf, for those that interested in integrating Powershell within their Chef recipes.
The presentation highlights the use of guard to evaluate conditions during execution on the chef client, guard interpreters to evaluate string commands and also the integration of Chef with PowerShell Desired State Configuration (DSC).
For those interested in DSC, check out the following for more information – http://blogs.technet.com/b/privatecloud/archive/2013/08/30/introducing-powershell-desired-state-configuration-dsc.aspx.
Deans Blog 