The first time I tried this the entire blog came crashing down. I decided I’d wait until a night when I had more time and that night didn’t come for another few months until tonight. This time I elected to follow an incremental upgrade approach by moving from 2.0 to 2.1, 2.1 to 2.2, 2.2 to 2.3 and so on and hitting the wp-admin/upgrade.php file after each upgrade had completed. Of course I was careful not to overwrite the wp-content folder. It worked great and I’m loving the new interface.