The Multi-Window multitasking introduced by Samsung on the Galaxy Note 2 is probably one of the most lusted features in the Android community right now. While Samsung originally introduced the feature on the Note 2, it will be bringing the Multi-Window multitasking to the Galaxy S3 and the original Galaxy Note as well via the Android 4.1.2 update. The Galaxy S2, however, will not be getting the Multi-Window multitasking update probably because of its lower resolution screen and small screen size, which makes the multi-window multitasking kind of redundant.
Even then, some of the developers over at XDA forums have managed to port the Multi-Window feature to the Galaxy S2. The mod will only work on the leaked Android 4.12 XXLSJ firmware for the Galaxy S2.
As clear from the screenshot above, the multi-window mod is not really useful on the Galaxy S2 because of the low resolution screen on the device. Even then, the mod does bring you bragging rights and it might just be useful for some people out there.
If you own a Galaxy S2 and are interested in the Multi Window mod, then head over to this thread on XDA forums and flash the attached ZIP file via CWM.