I successfully compiled an AMD64 binary on Ubuntu 11.04 64 bits, and it runs OK as long as don't move the mouse in guest OS (OSX 10.4 Tiger).
Doing so for a few seconds just freezes the mouse, while the console infinitely spits "[IO/CUDA] <Warning> Event processing timed out. Event dropped."
This very same bug was present on a Redscorp's release. He managed to fix it in the next build.
According to some Darwin developper I talked to, this could be related to a non-emulated video framebuffer.