One of the things one learns is that one can often be right without saying much. For months as the JoltID suit has been rearing its ugly head I've been saying Skype is a brand not a technology and they would simply go all SIP. That opens the door to a lot of potential moves, but one that makes total sense is buying Gizmo from Michael Robertson.
It makes sense because Gizmo works, but what really makes it interesting is how GoogleVoice already has a peering relationship with Gizmo ( a deal I helped broker two years ago when both were just simple startups per se)
The peering means if Skype goes with Gizmo as it's SIP backend is that calls to and from GoogleVoice are FREE and the stay on-net, without ever touching the PSTN.
Unless I'm mistaken though, Gizmo isn't P2P SIP, but just SIP, with of course the media path being P2P like all VOIP, and the Signaling being SIP.