Well, the reverse order is an interesting idea, especially for long threads. However the various online forums that I have viewed recently are in chronological order. The reverse order would be useful if you just want to see the most recent post. But the chronological order is more convenient when reading through a long thread for the first time. My vote – stick to the regular chronological order. If we want to get fancy we could add a button to take one to the last (most recent) post.