Google+ is in it's beta mode, and aside from the fact it keeps sending me to the mobile site (you can change to desktop at the bottom), it looks pretty slick. Works at least as well as FB.
They offer some type of video chat (wanted to try it out on the PB), but the option looks unselectable for now.
The only downside is that you must register for Goolge+ on a desktop/laptop, then you can use your PB to log in. They also have an Apple and Android app. Blackberries running OS 6.0 can use the web interface. Hopefully they come out with an app for Blackberry, but if not, it works just as well via browser.