In the next day or two, WP 2.0 should be released (I believe the final RC was let out today, for any last minute bugs). Which means now would be a great time to backup all your files, including your database. Even if you don’t intend to grab a copy hot off the press, backing up is always a smart move. It’s much easier to learn how to import a DB into a clean install, than to learn the hard lesson of not having files backed up (see miklb start backing up his laptop now).

For more details, and links to articles covering how to backup, what’s new in 2.0, and general discussion see this thread in the support forums.