From the Gmail blog
As the holiday season approaches, we’re happy to announce that we’ve extended free domestic calls within the US and Canada for 2012.
This is our way of helping you connect with friends and family across the country. And you can still call the rest of the world from Gmail at our insanely low rates.
Now, you don’t think that this has anything to do with Google’s attempt to have us all ultimately do everything through, or at least connected to, Google+? Nah. They wouldn’t do that now would they?!