Just upgraded to WordPress 2.3.1. So far so good. However, it would be nice if they would keep all user-added files in a single folder. As it is now, any added plugins and themes must be remerged in. There’s no reason that the included distribution themes and plugins have to be in the same directory as user-added themes and user uploads. It makes no sense, and renders the upgrade process a much more laborious enterprise than it really has to be. Good design would dictate segregating everything the user might want to add or change into a single directory that wouldn’t have to be touched during an upgrade.