Ball entering basket from bottom

[ChuckElias]

Originally posted by cford
So there is a spot throw-in on the end line awarded to the team opposite of the player that last touched the ball. Is this correct?

Yes.

Does anyone have a rule/case reference?

It's rule 9-4. It's discussed in case 9.4. Note that the rule explicitly states that the ball must enter "and pass through" the basket from below.

Has this ever happened to anyone?

I'm sure it has, otherwise it probably wouldn't be in the rulebook. I've never had it happen in one of my games, however.