I installed WP 2.1 and everything works well except one glitch so far. I have no problem saving and publishing posts from either the Visual or Code Editing windows when they are short. However, I wrote my first long post and now it will only save or publish from the Code Editing window. If I try to save or publish from the Visual window, it gives me an internal server error. I repeatedly tried with short and long posts. The short posts work in either window, but the long ones will only save or publish in the Code window, so I always have to switch over to it to save, which is a pain.
I did notice one interesting thing which is that if I put a piece of the long post, save it, then put another piece, save again and so on, then the long post will save gradually that way in the Visual window. But if I just put the whole long post in and hit save in Visual it won't work. If I switch over to the Code window, it works.