There's one we attempted to use in school for p2p messaging over the network. [1]

I also came across a chat system for the Plone CMS. [2]

[1] http://sourceforge.net/projects/babble-chat/

[2] http://babblechat.org/en/latest/

Yes, there is. Link: http://domino.research.ibm.com/comm/wwwr_thinkresearch.nsf/p...

Not entirely related to Google's idea, but not completely unrelated either.

There was a 'go' language before Google's Go. There were products named 'iPhone' before the Apple iPhone. If the prior use is obscure enough, and you can afford the legal/buyout costs, a name collision isn't necessarily fatal.