It was introduced last year.
The good news is that you can call for free people living in the United States and Canada for now and up to the end of 2011, as Google wrote in its blog.
It works if the voice and video chat plug-in has been installed on your PC.
We can globally save money by using the Voice and/or Video chat feature of CevApps to call colleagues.
I know that many of you use it regularly and I think that by itself it may reduce the cost of communication, specially long distance / international.
Switch from emails to chats and voice or video calls when you can, this can help the fight against email overload.