Although The Incredible Hulk pulled in a respectable $55 million on this, its opening weekend, that was no where near Iron Man's approximately $100 million.
Unfortunately, Hulk underperformed slightly this weekend compared to the $60-70MM the studio hoped for, but let's see how it does next weekend and thereafter. On the other hand, the abysmally awful The Happening actually exceeded expectations, bringing in $30.5MM. I can't wait to see THAT movie's numbers next weekend - if there's any justice in the world it'll bring in less than $16MM and go down from there.
On the other hand I have a feeling that good word of mouth will keep The Incredible Hulk afloat with probably another $33MM next weekend.
Although there was a big marketing push in the last couple of weeks, this film just didn't get the monster buildup that was given to Iron Man prior to its release last month. A combination of confusion over whether this was a reboot or a sequel (it was a bit of both), lack of awareness that the movie was even coming out and the memory of the less than inspiring Ang Lee version conspired to put a lid on the box office numbers.
I see the same thing happening with the Punisher movie being released this Fall, except even moreso since that one will be rated R and thus lock out some of the teens and younger audience members.
Also I'd say this is a testament to just how great Iron Man was considering how relatively unknown of a character he was to the general public before the marketing blitz started.