Despite a couple of people pre-announcing it, PostgreSQL 8.3 was actually fully announced and released about 40 minutes ago. Announce email should be going out, and the press release is available. Instead of just reiterating the new features, I'll point you to the list of cool new stuff. Or check the release notes.
If you haven't tested your apps with it during beta or RC time, now is the perfect time to do it!
There, I just had to get this one in before Devrim did. Ha! I win this time!