The boys fell a tree the other day that had a few baby squirrels in it. They brought them home and now we are trying to raise them. I did a little research and found this website to be very helpful: Squirrel Tales. We are following the instructions given on that site and so far the squirrels seem to be doing ok. Based on what the site says, I guess these babies are 2-3 weeks old.
Here is a photo of their bed - there are actually two bottles of hot water and the squirrels sleep in between. This helps to keep them warm :)