It's been around since 09 but I've never used it. You used to have to get an invite to get it but I think it's open to everyone now. I was reading this article about it and it looks like it's pretty neat. It's definitely got a lot of features that most services don't offer or that they charge extra for. If you don't use it check this article out, if you do let me know what you think about it.

What Is Google Voice