Don't think so, that's why it's cool to see it coming to WM.
The closest thing we've had to a voice changer is screaming bee's voicetwister:
http://www.screamingbee.com/product/VoiceTwister.aspx
Problem with voicetwister is it doesn't change your voice in realtime. You have to record then play it back. Kind of takes the fun out of it. Let us know if you find something else tho.