After watching the Sonics game I'd have to say Watson would be a perfect point guard for the Celtics. It'd allow Boston to dump Telfair and give Rando someone he could actually learn from. It'd also mean West would only have to play the point in emergencies. Watson has had problems with his role in Seattle, although things seem to be better now.
I don't really expect this to happen, but he's one of a few players that might be available that would really help Boston, and he wouldn't cost them too much.