Terrence Howard revealed to Military.com that Iron Man 2 is scheduled to begin filming in March 2009. This seems a good idea as Marvel have already claimed a release date of April 30, 2010. This gives them just over a year to get it all complete.
Jon Favreau is expected to direct again, with Robert Downey Jr. and Gwyneth Paltrow returning as well. However, if you want to see a bit more of Tony Stark then go and see his cameo in The Incredible Hulk.