So AJAX RTM was just released and WebParts still do not work properly. Sadly this seems to be a low priority for the ASP.NET Team even though people (especially me) have been complaining about this on the forums since beta 2. The “official” word is that it will be fixed when Orcas is released.
I have in fact written my own less–featured WebParts equivalent; however it would be nice if Microsoft could just get theirs to work. There’s no point in reinventing the wheel if you don’t have to.