This has to do with dissolved gasses which escape on opening changing the freezing point, not the inability of water to destroy an aluminum can. Freezing water fractures solid rock, creates pot holes in roads, and has no problem breaking a thin aluminum shell.

Interesting, thanks. That won't stop me from putting beer in the freezer though.

Gp ahead, just don't do it with beer bottles. It takes quite an effort to remove all the little shards of broken glass and the fridge smells like beer :)

I've never had that happen, but wouldn't the cap come off first?

Apparently not; I've had a bottle of soda 'sploding in my freezer. I'm guessing that since the bottle's neck is so slim the water there freezes first, effectively "plugging" the bottle.