I think you can try out the demo but there is a big annoying box that tells you to buy it until you enter in your registration code. I'd buy it though because its a pretty good app and to me is worth every penny.
Konfabulator is a great product though. I hope the Tiger version is as polished.
I feel sorry for the Konfabulator guy.. I would hate to have my software product built into the next version of the OS. there goes my source of income!