I'm sorry for the really long delay. It took me a while to get up the motivation to write the updater from 2.0-beta9. It's not pretty. It's really quite ugly, but it works (as far as I know) and it lets me get the much improved beta10 out there. The installer and updater are the ugliest bits of code and presentation I've written. If someone would like to make a project of cleaning that up, it's not a particularly arduous task.
So what's new? This is probably the biggest release in a while. The biggest change is the addition of support for timezones. Each calendar can be set to a timezone and users can change their timezone so they can see events at the appropriate time for them.
Calendars and users can have default languages.
Color picker for categories, thanks to Michal Osowiecki.
Generally, there have been a lot of fixes all over the place. Check it out, backup before you upgrade, let me know of any problems. Really, don't trust the upgrader. It's been tested by only me.
Update: I'm sorry, I shouldn't post when I'm distracted. I would like to thank, in no particular order, Michal Osowiecki, Pascal Rigaux, Marcelo Fortino, Hans Eksteen, and all of the people who reported issues but not their names.