I've been playing with IKVM and mono on my mac (and .NET on a winxp box). I'm amazed and excited. I'm going to see if I can get Geronimo running on IKVM and see how fast it is. Someone tested Derby on IKVM, and it was faster than J2SE 1.4. Could it really be that the best way to get java to perform is run it on .NET? ;)