I've been having trouble compiling a working copy of QEMU on Lion.
When I try installing through homebrew, I get a screen like this when I attempt to run QEMU:
The blank screen just sits there hogging the CPU.
Looks like the Lion compatibility issues are solved. I'm still testing this: http://www.rpiforum.net/forum/tutorials/article/16-a-raspberry-pi-emulated-environment-on-osx-lion/
Please try the latest v1.1.0 Release Candidate from http://wiki.qemu.org/Download.
If that does not solve it, post to qemu-devel mailing list how exactly you configure and run it.