So I've had Leopard for almost a week now, and I've only installed it on my iMac. I had originally installed onto an external hard drive, just to verify that all of my programs would work, and most of them did. One of the major programs that did not work was Talkshoe. Almost every other program has worked. XCode is excluded, since there's an updated Leopard version, which I haven't yet installed.
To see a rant on the supposed "Mac OS X Trojan F.U.D" head over to macgasm.net