I have the Comments Plus plugin installed, and it seems to be working with the FB integration. I have also set up the Twitter account, but I can't tell if the Twitter or Google tabs work because nothing happens when they are clicked on.
Check it out (comment form at the bottom of this page): http://mig.ht/MIGHT-on/redirection/
I have checked it in Safari and Chrome on Mac OS Lion.
Any help would be greatly appreciated.