To go along with the Linden blog post about Server Side Appearance (baking) Jessica has published an article on where the FS Team is with the next release of Firestorm. See: Server Side Baking on the Way!
Jessica is trying to get 145,000 Firestorm and Phoenix users to upgrade their viewers. These are just the users that are on older viewers that will not support SSA. She says the majority of FS/PH users have switched to the newer 4.4.0 viewer. Still 145k users is a bunch.
I expect the SL forum to get lots of new users when SSA is enabled on the servers. They’ll all be there asking WTH? Avoid being one of those people, update to a viewer with SSA support.