So far I see patches to the RIL, and something called Opencore and Webcore.
I'm seeing updated .apks for the typical apps (videos, phone, music, etc.) Possibly bugfix releases?
It looks like this update is able to wipe a custom recovery in some cases... so be careful.
There's also a Bluetooth update
Hopefully more BT profiles will be supported now. That'd be nice.
It also patches mmcblk0p1, mmcblk0p2, mmcblk0p9 and mmcblk0p12, which the updater script calls the "DBL image", the "OSBL image", the "AMSS image" and the boot image, respectively.
Will update this post as I find out more.