Going over to swipe.nokia.com shows following extra additions to PR1.2 improvements.
For now the probable changelog is what you can see in the above screenshot from swipe.nokia.com.
We will update you as soon as full changelog is available.
http://discussions.nokia.com/t5/Maemo-and-MeeGo-Devices/New-update-for-N9/td-p/1492192