This video posted over at BerryReview does indeed give you an idea of the durability. Crazy to think that your Blackberry can sit that long in water.  The video was put on youtube by phillipe80 along with this info:

My BlackBerry fell into the lake and I thought it was broken. I called T-Mobile and they would pick it up the next day. However when I turned it on the next day it was alive and kickin! So I tried it again and after 2 minutes I gave up. The BlackBerry just didn’t wanna leave me…