The morphological AA feature introduced with AMD's Radeon HD 6800-series graphics cards is an intriguing way of adding anti-aliasing to the unfortunate torrent of games cross-developed for consoles that simply don't work properly with conventional multisampled AA. We looked at it briefly in our 6800-series review, and I've been playing with it some since then. Preliminary verdict: it ain't perfect, but it's way better than the complete nothing you often get in current games. MLAA as AMD has implemented it is also superior to most of the console-style post-process filters out there.
Making it work has been a bit of a trial, though. If you own a Radeon HD 6850 or 6870, you'll want to grab the latest 10.10d hotfix drivers to sidestep a bug that caused the feature not to work in some games.
Owners of Radeon HD 5000-series cards don't yet have the option to enable morphological AA in the Catalyst Control Center, but we just received word that AMD is preparing another hotfix driver release for next week that will allow MLAA on those cards. If you have a Radeon now, you'll want to grab those drivers when they come out.
The performance hit for MLAA can sometimes be steep, but faster GPUs won't have a problem with it in many games. I've had good results in Medal of Honor's single-player campaign, for instance.
We also understand that AMD is working to improve MLAA in terms of both image quality and performance. Since the effect is generated by a post-process compute shader, the potential for refinements going forward could be considerable.
Update: Turns out the release of this driver may be closer than we'd anticipated. Stay tuned!