Finally, my moment! I submit my own library, which is really meant for two players and scoring...and like much of what I do, was purely pun-driven. Maybe one day I'll add AI:
Have a look at the Go Text Protocol [1] and SGF [2]. If you add these then the strongest existing AIs can already play on your board.
All that said you can of course write your own bots, but Copmputer Go isn't as easy as one might think. In fact it's still considered a much harder problem than Computer Chess.
