Wrox just recently put up a link to "Professional Windows PowerShell Programming: Snapins, Cmdlets, Hosts and Providers" (current link here).
This book was previously on Amazon for several months, and the due date has changed a few times and is now February.
This is another book I'm really looking forward to. I've written a few cmdlets, and would now like to get into writing providers just to go through the exercise.
