You don't want to put it in the freezer; besides the possibility of damaging something, you'd be hard pressed to get dead ants out of the device without opening it. I'd stick with one of the sugar/honey ideas.
just dont let the ants go back in the macbook with the honey or sugar...that would be messy
i dont know about fridge/freezer...youll have to watch for condensation. obviously turn it off and take out the battery...after you take it back out, wait a day or so to let it dry before putting the battery back in
edit: just thought of this - get one of those canned air deals and blow them out of there
Exactly, go buy FCP or something intensive (or just rip a DVD, I kid) and try to run it on your MB, that should make it uncomfortably warm. I dunno why they'd be in it though, maybe it's because it looks like a big shiny white tic-tac.
My girlfriend's MacBook made me LOL every time I used it. For weeks ants would appear from the crevices. Of course she lives at Starbucks and I am sure there were plenty of crumbs to sustain life. I would leave it adjacent one of those traps (just occurred that if you placed it too close they would crawl back in and then die).
MacBook -------2 ft---------- Ant Poison -----------3 ft---------- Pile o' Moist Sugar