The app is now available on the Market. It's called "Group to Voicemail" and is available for devices running Android 2.0 and above.
Here is the announcement post:
Group to Voicemail - Automatically send groups of Contacts to Voicemail
Here is the web page I put together for it:
Group to Voicemail | For the Gamer
If you have any questions let me know. I look forward to you feedback!