I know that 100ft + wave heights were registered in the October "perfect" storm (Discovery Channel) but it just seems impossible. I couldn't imagine a wave that high.
I've seen some footage from storms in Lake Superior taken from frieghters with 30ft+ waves and that was incredible. The water would just roll right along the deck of the ship. Those 1000ft'rs looked pretty small in those films. I don't think I would want to be on one at that time.