Eric Dumazet, one of the many kernel hackers, wrote a JIT compiler that compiles BPFs directly to x86 code _in the kernel_. Much to learn from his code: http://lwn.net/Articles/437884/

As tptacek notes, the VM is very simple -- it's straightforward to write a BPF VM to C-code translator that you can then compile by gcc. But it will still be slower than edumazet's compiled code.