The Celts also received the nice benefits of two goaltending calls or no calls.
Yeah, the Rondo one was a horrible no call. I don't even see how Tommy could back that lack of a call. Well...maybe Tommy could spin it, but the rest of us... 
Actually, it was the correct call in that instance. For the most part, once the ball hits the backboard, it's on its downward trajectory and should be called a goal tend if touched. However, in that particular instance, when Rondo made the block the ball was on the backboard yet still below the rim, since it hit that part of the very bottom of the backboard which extends below the rim. By rule, any ball still below the rim cannot be goal-tended. Rondo blocked the ball before it got above the rim--that's why it wasn't called a goal tend.
Goaltending criteria:
e. During a field goal attempt, touch a ball after it has touched the backboard below the ring level and while the ball is on its upward flight.
Even if the ball was below the ring as you're saying, it was an underhand shot and was most certainly going up.
Regardless, I found this interesting, as it is like a universal copout for a bad call:
c. For goaltending to occur, the ball, in the judgment of the official, must have a chance to score.
Ha.
http://www.nba.com/analysis/rules_11.html
Wow, I stand corrected. I guess once it goes up on the backboard it's a goal tend no matter what, even
if the ball is below the rim. It doesn't make sense to me, but I guess that's the rule. You'd think it would be impossible to goal tend anything that's below the rim...
As for the shot in question, I'd love to see the replay too, just to make sure. My recollection is that Rondo hit the ball before it got above the rim. As we were watching the replay on TNT I told my fiancee that it wasn't a goal tend because Rondo hit it before it got above the rim.
But, since it's a goal tend any way you cut it, the official must have made the judgment that it had no chance of going in. Going off my memory of the shot, that was probably the right call...