Finally, there is an ATA device available to allow you to use your Google Voice service. http://obihai.com/ has created an ATA device that works with many VoIP providers - INCLUDING Google Voice.
Now you can connect your Google Voice number directly to a phone with out having to do any tricky set ups. Best of all your outgoing calls will show your Google Voice number, so you do not need to dial into your Google Voice number, or use the click to call features to make your GV number appear on the outgoing caller ID.
Seems like the cheap/free unlimited calling market just got a whole lot more interesting. This device is cheaper than the Ooma and Nettalk, and only a few dollars more than the Magicjack - BUT you can use Google Voice, so as long as Google Voice keeps their price at free even just for another year this unit is the cheapest alternative to land phone service.