Fox’s Dr. Seuss’ Horton Hears a Who! reached the $150 million landmark at the U.S. box office this week, becoming the 25th highest grossing animated film of all time according to Box Office Mojo. The Blue Sky feature is also performing strongly overseas with a cumulative worldwide gross of $284 million to date which is still enough to qualify it as the #1 movie of 2008 for a few more hours until Iron Man takes the crown. Horton should pass the $287M worldwide gross of DreamWorks’ Bee Movie in the next week though, a feat all the more impressive since the Dr. Seuss adaptation reportedly cost half as much to make. Update: Iron Man flew past Horton over the weekend to become the highest grossing film of 2008.