mtgox accounts can be easily considered an assest, thus giving the info to your estate lawyer or 3rd party could work.
But what prevents them to steal it? I mean, I have to give the passcodes?
I'm trying to think in a good manner to leave digital currencies at my will. You have to give the passwords for somebody, otherwise it will be lost if you die. The best way to give a password to somebody it's not giving the real password, printed on paper, but a mixed one, like backwards, or going up in the alphabet 1, 2, 3 times etc. So you don't have your printed password floating around. What do you think?