Two new summer blockbusters will attempt to knock Iron Man 2 out of Number One this weekend At the Movies: Shrek Forever After and MacGruber. Shrek will likely end Iron Man's reign thanks largely to one secret ingredient: 3-D. This is real deal 3-D, however, and Shrek Forever After improves upon Shrek the Third, the low point of the series. Mike Myers, Cameron Diaz and Eddie Murphy once again lend their voices as Shrek travels to an alternate reality after making a deal with the trickster Rumpelstiltskin. Bottom line: kids will love it.