It looks like a yummy Ice Cream Sandwich ROM was leaked for the international version of the Samsung Galaxy SII (model I-9100). The build date is December 7th, and it was built around Android 4.0.1. Interestingly, it looks like Samsung's TouchWiz works fine with the new OS, although there are a few small issues overall. Here's a quote from the source with more info on what works and doesn't:

All the Basics work like calling , sms , internet and more.
Some applications havent been worked out correct so they will force close on stress.
Because we are dealing with a “CUSTOM” ROM here it can occur that the phone will react very slow from time to time.
There is also the chance of some “RANDOM REBOOTS”
We at Sammobile advise people to not use thhis ROM for daily usage.
If you want to download this firmware then you can do so via the provided link below.
The video is pretty dull for the most part, but shows off what it needs to nonetheless. They do mention that if you are used to only flashing stock roms that you should not use this one. If you want to risk trying it out, check out the SamMobile.com source link below.

Source: TalkAndroid and SamMobile