Many of this ideas about "graphical" detection of shapes have bee tried. The good news is that all of them work, the bad news, they 're not enough accurate. I think that all strong Go programm use such things, plus pattern matching algorithm, some life & death specialized engine, and some quick hashing. If you want to see how works a Go programm, see GNU Go sources. other available free programs are Baduki, Gtk Go and a fee others. I'd like to see more contributions to these two last, to have more competitors for GNU Go... Currently, most of major programs fights again each others on the computer go ladder. True hackers should find the related links themself
;-) To mention : there is a bunch of go related softs on Mandrake contrib CD.