Saw this elsewhere but its a video on the Formula1.com website of the drivers wishing Kubica well, as well as some light banter: http://www.formula1.com/news/headlines/2011/3/11788.htmll
This is proably the most relevant thread for this. A pricture of Kubica's arm: please log in to view this image Hope he recovers.
The actual hand looks in surprisingly good shape. The damage looks as though it was mainly to his forearm. It looks healed so he'll probably be starting his rehab, hopefully he'll be back in the car before the end of the season, even if it's just Friday morning's or driving an older spec.