There have been some more bugfixes applied, and there is now a second RC available. Details are in Ryan Boren’s announcement.
WordPress 2.2 RC2 — You’re soaking in it! (In other words, I’m running it here 😉 )
By the way, one other change in this version that I don’t think has been mentioned in the previous announcements: In the “Write Post” screen, the post preview is no longer displayed directly in the page. Instead, you’ll find a “Preview” link near the title area which will pop up the post preview in a separate window. This speeds up page loads and reduces bandwidth consumption during post editing.
See also: the Release Candidate 1 announcement.