Perhaps I should be ashamed to admit this, but back in the summer I have to confess that I did see a little bit of Channel 4's Big Brother. At one point one of the guys - Maxwell? - was complaining because someone else had frozen his beer, and it was thus "broken". This sparked a discussion amongst the group I was with (see, I wasn't the only one) as to what would happen if you did freeze some beer and then defrost it, and whether it really would ruin it.
So I decided to experiment. I popped along to Sainsbury's and duly purchased a can of Carlsberg Special Brew from the 'Reduced to Clear' section ("it was cheap"). Upon returning home I placed it in the freezer and, for some reason, forgot about it completely...until two days ago when a frozen-solid can of Carlsberg Special Brew was found, wrapped in a carrier bag, in the freezer as we moved house. It was kept frozen for the move and now resides in the freezer here temporarily. I plan to defrost it in the next couple of days and see what sort of results my experiemt will yield; I'll publish my findings here in due course.
I don't know that it will be a particularly fair test however - I've never knowingly had Carlsberg Special Brew before in my life and for all I am aware it could taste rough even before it's been frozen and defrosted.