Dreamworks' Monsters vs. Aliens 3-D animated feature will now open on March 27, 2009, instead of the originally scheduled May 15th.  The move is to create more space before the release of James Cameron's Avatar, another 3-D feature, on May 22nd. 

Several of the big weekends for 2009 had seemed set (see 'Monsters vs. Aliens Debut Set'), but in addition to the change above, Variety is also reporting that the third Chronicles of Narnia feature is moving from May 1st, 2009 all the way out to May 7th, 2010, due to a delay in the start of production.