GrooVe IP - Android App for Google Voice via 3G/4G & WiFi
It had to happen.
Hot on the heels of the OBi110/110 ATAs supporting Google Voice now the first Android App which supports Goggle Voice via XMPP and 3G/4G & WiFi.
The app is called GrooVe IP and it is in the Google Market and possibly elsewhere. The author is charging a modest fee but the application does seem to be getting active support. I have tried on both the Thunderbolt and G2.
I hope that Google don't start to block such efforts!