The AT&T Galaxy S II got updated to Ice Cream Sandwich this past June, but tonight there are reports of users getting a slight version bump to Android 4.0.4. The LK3 update can be retrieved from Kies, but luckily users are saying they downloaded it OTA as well.
There is no change log available, and so far nobody has found much difference from 4.0.3. We doubt that the Exynos patch is included, but we'll have to wait until more people get it installed so someone can check. Of course even the smallest bug fixes and security adjustments are appreciated.
Source: XDA. Thanks, Matt!