Points were just virtual things awarded for posting/creating a thread. At one time way back in a time now lost, they were actually used to "buy" Diablo 2 items from other members, but the whole system was quickly abused and abolished.

It was brought back later, and there was a forum store where people could buy some forum modifications, like being invisible or changing someone elses custom title or whatever. Then, there was a lottery system with the points, and once again was abused, thus ridding the point system once more.

Right now, AFAIK, there is no point system, and I don't really see a reason to have one, when it will just be abused again somehow. If there was a system, you'd see information about it on the left of people's posts.