As is common with every release of WordPress, once the stable version reaches the masses, that is when the bug reports start flying in. WordPress 3.0 is no exception. However, the volunteers that make up the WordPress.org support forum are on top of things and have created a special sticky thread which lists the most common problems being reported as well as solutions. So far, the podcasting plugin by TSG, HeadSpace2, Event Calendar, fatal error due to allowed memory size being exhausted, and stuck in maintenance mode are being reported the most. I’ve upgraded WPTavern to 3.0 today and didn’t experience any issues. However, had I needed to revert the site to the previous version, BackupBuddy would have came to the rescue.
How did your upgrade go?
Pretty seamless. Oddly, the wp-db-backup plugin, which I ran before doing the upgrade, failed on one of my sites, but that can hardly be blamed on 3.0. (Random glitch, perhaps, since it worked properly half an hour later.) Otherwise, no issues so far.