Download this
http://sites.amd.com/us/game/downloads/Pages/crossfirex-app-profiles.aspx
I have tested it myself and crossfire works perfectly now
download the latest catalyst control center too just to be safe

yup, i can confirm:

ATI Catalyst Application Profiles 0.5 MB 11.3 CAP1 3/31/2011
Description:
This release of ATI Catalyst? delivers support for the latest ATI CrossFireX? profiles in a separate executable file ensuring users have access to the absolute latest set of profiles installed on their PC.

New profiles added to this release:
- Crysis 2 (Steam version) – resolves flickering seen when running in CrossFireX configurations.

bump

People need to know!

Now, how come retail version buyers do not get any fix? What's different in steam version, apart from being patched to 1.2 and restored to 1.1 in ~30 mins?

Also, does this resolve flicker for real for steam users? How's performance?

Has anyone tried if this also fixes the problem for non-Steam users without having to use the workarounds? Sounds just weird that it'd only be fixed for Steam users.

Didn't reboot computer but afaik it isn't needed when installing profiles.
Nothing changes (of course, I renamed the game to Crysis2.exe)

It stopped the flickering for me (running a 5970) but the performance is awful, I'm talking single card performance awful.

I used radeon pro instead with the fear.exe profile and I get decent performance with minimal flickering, not perfect though.