ATI has released Catalyst 6.7 drivers
for Radeon cards. Besides some issues being resolved, this release sees enhanced Crossfire support. What's that you say? From the release notes:
This release of Catalyst® introduces Enhanced CrossFire™ Support. The enhanced support allows for CrossFire™ Alternate Frame Rendering mode for Direct3D applications to be forced on by setting the Catalyst® AI slider to the Advanced position. This enhancement is available for all Direct3D applications except for Direct3D applications known not to work with Alternate Frame Rendering.