Gmail Call Phone
It looks like the Google Buzz feature roll out has been a great success for Google as they are applying once again the same strategy on Google Voice: Just Stuff it in Gmail.
It really makes sense to use such a large loyal user base for mass roll out at the same time without the need to fill applications and get familiar with a new platform from the end-user side.
As of today, you can call any phone from within Gmail. You will need to install the voice and video plug-in
According to Google, calls to the U.S. and Canada will be free in 2010 and low rates on international calls ($0.02 per min to major european countries including the U.K., France, Germany as well as China and Japan. You can check the complete Google Voice calling rate here.