Today Linden Lab posted an update on the Sunshine Project, which includes Server Side Appearance (SSA) (baking). You can see it here: Faster Avatar Loading on the Horizon.
This is a warning that failing to update your viewer is going to be a problem. In my mind it seems they are somewhat downplaying the aspect that this update is going to cripple users that fail to update. Those that like the old 1.23 viewer and older versions of Phoenix are going to need to change to a newer viewer. Singularity seems to be the viewer of choice for those users.
Most third party viewers have the code needed to use SSA. Firestorm added it in their most recent release (4.4.0). Most of the others have too. When SSA is activated if you start seeing ONLY gray avatars, you need an update. Nothing breaks by using the older viewers. You just won’t see avatars render. They will stay gray… forever.
Part of the Sunshine project is changes to how the viewer and servers communicate. The viewers use HTTP and UDP protocols for communication. Much of the communication is changing over to HTTP and the code that controls the HTTP and UDP channels is being modernized and updated. From those changes we should see improvements. I think that is the second part of the improvements the blog is referring to. We’ll find out as the Lab moves forward.