IGN heavily qualifies what it heard at Comic-Con '08, and it isn't confirmation. But any idiot can look at Mortal Kombat vs. DC Universe, especially the fact it's getting positive response, and figure that Marvel and Capcom have some kind of response.
Anyway, IGN reports that at Comic-Con, Kevin Feige, Marvel Studios President of Production (wotta title), was asked if a new Marvel vs. Capcom game was possible someday. His reply: "Yes. And maybe sooner than you think".
IGN goes on to say that a Capcom under-production title, probably for Japan release only, could provide the guts for the game, allowing it to be turned around in a relatively short time.
New Marvel vs Capcom Game On the Way? [IGN, via Scrawl]