[Galaxy S II Android Development] JR-P20PRO:
I think its just error fixing.. I don't think it'll be the 2.9.7 update.. incase it is though:

[Recommended this week]
Add new telephone designated contact automatic recording function
The new lock screen Misoperation mode (waiting for everyone's feedback do further improvements)

[System]
Repair the the FC problems may delete millet account

[Phone]
Automatic call recording function (see set new designated contact -> call recording settings -> specify the number of automatic recording)
Optimize update numbers attribution to the database
After the end of the optimization of call recording notification bar prompt text
Repair vertical slide answer mode, another telephone call into the interface displays the wrong question
The fix input "*", T9 search no contacts
Repair dialed number with "#", unable to generate call records
Repair CDMA phone to hang up the telephone conference call may FC
Repair some cases display the English prompts the question (submitted by: @ Taiyuan - small facilities)
Repair may FC missed calls ringing prompted

[Contact]
Optimize the operation to add a new entry
Add failed, fix strange numbers added to a contact group

[Messaging]
Optimization in more than 200 text messages in a session, click "Show All information display
(Submitted by: @ jayhe2010) to repair more than 200 sessions, the latest a text message can not be displayed
Browse recommend the specific content of the SMS is fixed, not pop-up menu, press the Menu key
Repair some cases, the new SMS prompt window can not be closed
Fix some cases, restart the machine, SMS program FC (submitted by: @ Everbai)

[Lock screen, status bar, notification bar]
New lock screen Misoperation mode
Repair some cases, the problem Variety lock screen frame text elements missing
Repair Variety lock screen frame, some cases with the mask image animation beating
Repair status bar notification eliminated will still leave large gaps (submitted by: @ xzhlksh)

[Desktop]
Added support for the application is sent to the desktop gadget, such as notes
Desktop icons and optimize the new increase in the default location of Desktop Gadgets

[Themes]
Optimize improve the download speed for a list of online resources thumbnails
Repair the normal size 480P theme in 720P (Topic Resource adaptive size)

[Gallery]
Optimize pick from third parties to enter the gallery into the Gallery Home
Repair more than 256 Atlas, enter the "Atlas" page FC
Repair some cases, after the picture is taken, the photo in my photographs displayed
Repair some cases, FC problem occurred when cropping a picture
The repair cloud picture books in display details inaccurate.

[Music]
Optimize load efficiency of online music list
Repair telephone recording can not play music (submitted by: @ colorfuljoe)

[File Manager]
The file new favorites bulk unsubscribe
No network optimization, directly into the network disk will prompt "no available networks" (before optimization will spend a longer time to detect network environment)
Repair FC problems lead to extract the files in the network disk
Repair "archive" folder does not show the RAR file
SD card directory delete Favorites folder

[Browser]
Optimization will be preset bookmarks split as a shortcut Bookmark grouping

[Recorder]
Telephone access repair playback recording file, the audio file will not stop playing

[Calendar]
Repair some cases Lunar date display incorrect

[Notes]
Animation optimize new notes
To optimize grid mode mobile notes fluency
Optimize desktop sticky notes gadget supports free resizing
Repair backup and recovery will lead to the notes folder name is missing (the submitter: @ increased step by step)
Repair some cases, long notes lead FC problem (submitted by: @ 38.5 degrees)

[Other]
Repair without SIM card, it can not be closed "to retrieve the phone"
Repair some cases, the use of a combination of shortcut key screenshot triggers a one-touch operation

[Alarm clock]
New manual shutdown prompt an automatic boot rang the time, and you can cancel the alarm clock off

[Video]
Add a new version of the decoder, to increase support for more video formats, and smooth video playback
New new full-screen playback screen zoom mode
Add a screenshot function
To optimize playback control interface, increasing the Back button
Optimization can choose whether the video is automatically rotated
Optimize adjust the display for the interface of network video loaded
Optimize screenshot animation

as for CM10 Nightly updates, I haven't a clue.