Now that I think about it, splitting the book into two movies really opens up the possibilities for... are you ready? ... MUSICAL NUMBERS!
Can't you just see it? The final battle at Hogwarts, complete with jazz hands and West Side Story-esque finger snapping! Bella vs. Molly would be freaking awesome!
Oh! Oh! And Snape singing "In Your Eyes" as he dies! It's movie GOLD, baby!!
(okay, maybe it's time to lay off the coffee....)