Jeff Bauman Jr., as of this writing, is in stable condition. One of his friends posted an update on Reddit:
That's my friend Jeff in the wheelchair. This is the latest update I have on him. Google Person Finder says he is alive but for all I know someone saw this and reported him as alive. Carlos Arrendondo should never have to buy a drink in this town again.
EDIT: I didn't realize I could dive into the Google People Finder results. He was in the Boston Medical Center ER as of 23:20 UTC. Here is a photo of him from his facebook for verification: http://imgur.com/iL68E0w
EDIT 2: Received word via facebook that he is in stable condition. Thanks all for sending him thoughts and well wishes.