Matt has released WordPress 2.5 Release Candidate 2, and making a call, if you are interested in testing his new baby WordPress 2.5
If you make frequent backups and you are interested in helping us out with development by testing the very latest, download and install Release Candidate 2 of WordPress 2.5, and join our testers mailing list to report any bugs you find in the code
The community has started to keep a list here of which plugins work great and which don’t. Its worth looking at, or even better just deactivate your plugins before upgrading for 2.5 and let the built-in updater notify and give you one-click upgrades to plugins you have installed, assuming the developer is cool and has updated their code for 2.5 already.