Think you can save your friend if he falls into a crevasse? Can you even save yourself? This video might give you pause for thought.
Having done quite a lot of this it is easier with skis - although whether that would be the case if you were taken completely by surprise I can't say. In any even it reinforces the "rule" that a rope should consist of three rather than two climbers/skiers. It is also very hard to haul a stricken climber out of a crevasse with only one of you.
(thanks to http://kairn.com/ for the heads-up)