First the good thing: I updated wordpress to 2.3. Now the bad thing: I updated wordpress to 2.3.
With 2.3 there where many infrastructure changes. For a complete list, see the Release Announcement. The most extensions breaking change was the implementation of native tag support. Referencing to Not working Plugin List Ultimate Tag Warrior and Extended Live Archives are problematic. Both caused troubles on update, but there is a fix for ELA and one for UTW. By reviewing the informations for writing this article, I noticed that I'm running fine with the Ultimate Tag Warrior Bugfix Release provided by Christine from the Internet.
My theme K2 was needing also an update, which caused the style to be broken. So waiting for a fix did take little longer, but when reviewing it, I noticed that only a css class name did need an update.
This all teaches me, when using a project with much dependencies, it will be a mess when updating, as long as isn't all provided by one source. It's some kind of using a project "still in development".
Update: While we are at "still in development" .. I updated to 2.3.1-RC1 some seconds ago. :)