I got vfork() working well now, and exit() and execve() play nicely too. There were initially some memory leaks when doing a vfork() and then execve(), but those are all plugged now. I also fixed a few other bugs (one in heap.c, the memory manager) along the way.
I just released beta 3 demonstrating these awesome (in my mind at least) features.
Download it now. Also read the release notes.