HA! The built-in server finder is NOT as good as GameSpy! Puh-leeeezzz!!! Sure, it gets the job done, but then, what happens when the master server is down, and you can't find a game at all? That happened to me yesterday. So, I just used GameSpy, and got into the game!
Anyway, the initial post probably came about because the guy didn't realize that the Unreal Tournament executables are in the /unreal tournament/system folder. It's just a little quirk you have to be aware of. But, yes, GameSpy DEFINITELY works great with Unreal Tournament. Funny thing, though, it doesn't support the retail version of Quake 3 Arena. Could be because IT SUCKS A$$!!!