This sucks. Basically, half of Marvel's films just got pushed back a year because of Spider-Man 4. Not that I'm against Spidey, I'd just like to see some other stuff we haven't seen yet.
So, here's how it stands now:
Iron Man 2: May 7, 2010
Spider-Man 4: May 6, 2011
Thor: June 17, 2011 (pushed back from 2010)
Captain America: July 22, 2011 (pushed back from May)
The Avengers: May 4, 2012 (pushed back from 2011)