I dunno if it's been posted before but I made a search with "capcom play system 3" and "mame" and did not find any results.
Anyways, back on topic, CPS3 games are now playable on emulators. Actually last June pa, but I only found out recently, so... ayun. Eto yung mga famous titles previously unplayable on emus:
JoJo's Venture
JoJo's Bizarre Adventure
Red Earth (aka: Warzard)
Street Fighter III: New Generation
Street Fighter III, 2nd Impact: Giant Attack
Street Fighter III, 3rd Strike: Fight for the Future
So if you ever wanted to play SF3 on M.A.M.E. before but can't, you can do so now. Read for more info:
http://www.romnation.net/forums/thread.php?threadid=9604&sid=0f4ee01bcfda486fccfd00737f35c9cf