While were waiting for an official ROM, SamMobile leaks a new Samsung Galaxy SII ICS ROM.
The firmware was created on January the 29th so it is a pretty fresh ROM.
SamMobile says this ROM is stable enough for everyday use, so it seems as if your Samsung Galaxy SII will have the best 4.0 experience.
The changes include a 3D fluidity when scrolling and battery life also seems to be a major improvement.
If your the type of person who likes to take risks with their devices you can go check this ROM out.