[T-Mobile Samsung Galaxy S II SGH-T989] ElectricBubble:
ROM Changelog:

Added MIUI.us Toolbox for some nice customization - 6/1/2012 (also updated to 2.6.1)

Fixed issue with not being able to send SMS - 5/28/2012

Fixed internal and external storage so that gallery and music now see both - 5/26/2012

Updated to MIUI 2.5.18

Fixed issue with themes not applying - 5/17/2012

Fixed graphical glitches - 5/16/2012

First release - 5/16/2012

General miui 2.6.1 changlog:

[System]

Fix some applications, pressing the back key player gif results in locking

Remove the "Disable" button to disable the system applications on app info page to prevent incorrectly shutting down core services which may lead to stability problems

[Phone]

Optimise light-sensor strategy to tackle screen lighting issues

Optimise (CDMA) call ended still shows the green return to call information

Fix problems leading to FC caused by database errors

Fix in some cases the answering interface, vertical slide does not show the correct details

[Messaging]

Fix creating new message from the contact list of selectable contacts does not disappear after choosing contact(s)

[Lock screen, Status bar and notifications]

Added support for displaying music spectrograph animations

Optimisation without SIM card will display the phone in Airplane mode

Optimisation of lock screen to provide 720P HD support

Repair the wrong call in green text colour problem

[Desktop]

Added support for 720P resolution icons on desktop

Adding 4x4 Music Widget playing music sometimes leads to desktop not responding

Fix in some cases the Desktop widgets cannot be used

Fix in some cases long pressing the desktop (Home) button to open recent tasks list causes FC

Fix problem updating the default wallpaper

[Themes]

Optimise package download logic

Optimisation of theme thumbnail masks, description text is now clearer

Fix in some cases online themes does not show listing

Fix in some cases theme manager FCs

Fix select "Ringtones" through other applications such as Music player cannot play problem

[Camera]

Fix in some cases the scene mode cannot be opened from the function menu

Fix open shutter for zero delay, restoring the default camera settings still sets size to 8M pixels

Fix restoring video mode default settings and returning to view finger screen leads to FC

[Gallery]

Optimisation of the image details page, double-click the small pictures are enlarged up to three times that of the original image

Optimisation, the filter does not display the size of a picture of 0 bytes

Fix image details page animation when opening pictures

[Backup Manager]

Added support for backup and restore of emoticons, lunar calendar / birthdays and Network Assistant (Monitor)

Fix problems restoring MMS attachments

[Settings]

Optimisation to indicate incoming Bluetooth file transfer interface layout

NEW Allow to show / hide system FC error messages (See developer options for further details)

Added restore factory default settings can be opened to delete application(s)

New Factory Settings

New Bluetooth information display and phone name info

[Download Manager]

Optimisation to delete all entries, exit edit mode more efficiently

Repair the switch "To download / download / downloaded" leads to potential memory leak problems

[Calendar]

Fix creating a birthday notice is not updated in calendar

Fix delete a contact's birthday calendar, birthday reminders to all empty (also requires you to manually clear the data: enter "calendar store" in the Application Manager, click the "Clear Data" button) (05-31)

[Browser]

Optimised the default setting is turned off for "Automatically adjust page" feature to solve the wrong layout of web pages in some cases

[Traffic Monitor]

Optimisation of traffic usage over limit, status bar prompts once per day only

Sources: http://forums.miui.us/showthread.php?20329-ROM-6-1-2012-MIUI-us-4-0-4-2-6-1-Ice-Cream-Sandwiched

http://miuiandroid.com/community/threads/miui-rom-2-6-1-change-log.16803/

In case you havn't been following the thread Miui 2.6.1 can be found here:

http://goo.im/miui/hercules