You probably heard the rumor that Google Voice is now porting numbers. It seems the experiment started but mainly for mobile numbers. Why mobile only? E-911 headaches are less with mobile numbers than with landlines, I think.
Saw this yesterday: Cisco Killer OBi110 Puts Google Voice on Any Phone. It is supposed to replace Cisco's SPA3100 series of VoIP gateway and router powered by Linux. And it cots $50.
"Cleverly using the XMPP protocol Google has employed in its communications’ products, Obihai’s firmware adds the ability to make or receive free Google Voice calls on any telephone attached to the device."
This makes selling Residential VoIP even tougher, I think. But there is a market for selling and installing this hardware along with Google TV, HDTV antennas, and many other gadgets that consumers want but can't figure out. Break/Fix model would also work here.