IM+ from Shape Services does Google Talk and I think it does group the chats, like you are asking for. I keep flashing roms and don't always reinstall it but I will try to get to it later today and let you know for sure.
Or you could download a free 7 day trial and check it out for yourself. While the app does cost $39.95, I have tried many others and personally enjoy this one enough that paying for it was a no brainer for me. Also, it is a one time purchase, all further updates are free.
http://www.shapeservices.com/en/prod...php?product=im
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