I don't have time tonight to do the update but it looks like there quite a few bits and pieces in it in it. It seems the vanilla handsets, i.e. the ones without any carrier changes to the OS get it first followed by the carrier versions.
A new browser that supports HTML5, new widgets, a better music player, Microsoft apps and Nokia Maps 2 are built into the OS rather than being add on Apps. It looks like the N8 will get some extra built in imaging apps as well.
It looks as if the update can be done either OTA or via Nokia Suite.
This is pretty good support from Nokia.