Google announced they'd purchased Gizmo5, a Voice over IP company. Gizmo5 is a competitor to Skype. It lets you make free Internet based phone calls and cheap calls from your computer to someone's phone. They've closed Gizmo5 for new users, but old users can continue to use the service.
The technology meshes well with Google Voice and could add some much needed features, including the highly requested ability to dial numbers with extensions. Future Google Voice users might also have the option of making phone calls without having to use their phone. Given Google's preference for ad sponsored technology, it could also mean they'll figure out a way to keep it "free" for consumers by utilizing that pause between dialing a number and hearing a voice on the other end.