Another quote direct from Dirty Donny's blog (http://www.dirtydonny.com/new-blog/):

"New pinball with Stern

It's exciting to announce to you that I am in the middle of doing a new secret title on a pinball machine with Stern. If you liked Metallica your gonna love this one! It is also the reason I have mostly been posting older artwork and not new stuff. Stay tuned for updates!"

His line, "If you liked Metallica your gonna love this one" leads me to believe that he'll either be doing the artwork on Aerosmith or Iron Maiden (or maybe even Led Zeppelin if Stern somehow managed to secure that license).

Either way, it sounds like we can expect more Dirty Donny music pin art soon.

Batman Dark Knight was hinted as the next vault title by MNPINBALL (I can't find his exact post, but if I do, I'll link to it). He had also mentioned that BDK was one of the titles that Lyman was working on polishing the code for.