In addition to the further on-screen adventures of Tony Stark, Marvel has also announced Thor for July 2010 (I was wondering the other day if they'd make a Thor movie and if so how could this possibly translate into a big-budget feature), and The First Avenger: Captain America and The Avengers - which has no relation to that strange 1998 movie of the same name - for 2011. Cinematical is hinting that Samuel L. Jackson's appearance as Nick Fury in the post-credits scene from Iron Man was far more than a mere cameo and with this slate of upcoming films it does indeed look like Marvel is going to be building a cross-brand franchise: something that's never been done before with big-budget comic book movies so far as I can recall.
Cinematical also claims to have a source in the know who reports that in the sequel, Iron Man will take on the Mandarin (not really a surprise: they set that up in the first one with The Ten Rings terrorist group) and that Mandarin will set Fin Fang Foom on his titanium-clad nemesis (doesn't seem likely to me, but wackier things have happened). No doubt we'll also see James Rhodes put on the spare armor and become War Machine too 'cuz that was set up nicely in the first movie. Maybe even an adaptation of the "Demon in a Bottle" story too, which some consider to be the definitive tale of Tony Stark.
Oh yeah, Marvel also said they're doing an Ant-Man film too. If they're this serious about making Avengers movies, maybe they should go ahead and cast Kang the Conquerer? I nominate Michael Emerson, AKA Benjamin Linus from Lost!
(By the way, in case ya missed it here's my review of Iron Man from a few days ago :-)