Practically nothing Randy.
The code is pretty straight-forward. I've already got a prototype resident app up and running, but vb6 can't seem to recieve the game description so mine is on hold until I can port it to a more c friendly language. If anybody can successfully recieve the output description in vb6 then please let me know how you did it.
To better answer your question, it mostly depends on what powermame features you are talking about. If you mean the layout for each game (which was always silly to intergrate into mame) then the j5 beta I have in the sticky above does that right now. It can be launched prior to each game with a -justlight flag to light up yoru controls. If you mean controlling real arcade hardware, you'll have to wait a bit.