While I was excited to learn that NVIDIA had been working on a way to get AA working with StarCraft II even if the developer didn't take the time to implement one, I was disappointed to basically see no response from AMD and its driver team when I asked about the possibility of seeing it for users of ATI cards as well.  I truly think the majority of the blame should rest on Blizzard as the idea of releasing a PC game in 2010 without AA support seems simply insane.  And perhaps ATI will integrate AA override support by the official launch of the title but for now if you want AA with SC2 you are looking at NVIDIA as your only option. 

To enable AA with an NVIDIA graphics card, you simply have to open your NVIDIA control panel, set the anti-aliasing setting to "Override" and then set your desired level: 2x, 4x, 8x, etc. 

For those of you wondering if AA makes a difference for the real-time strategy game, I offer you the below examples and explanations.  AA adds to ANY PC game and StarCraft II is no exception.

1920x1200 1xAA - Click to Enlarge

Here is a scene from our REPLAY02 scenario that I think demonstrates how AA can improve your gaming experience pretty significantly.  If you look at the full screen image (1920x1200) you can see that there are "the jaggies" just about everywhere and very noticeably around the shields on the Protoss units. 

1920x1200 4xAA - Click to Enlarge

Here is the same scene with AA enabled - there is a noticeable difference as I'll show you below.

1920x1200 1xAA	1920x1200 4xAA

Here is a life-size cut away from the screenshots above; notice the edges of the blue shield, the edges of the units, etc. 

1920x1200 1xAA	1920x1200 4xAA

Now, as we zoom in a couple hundred percent to highlight the differences, notice the edges along the blue orb and around the outer lines of the unit in question: clearly the advantages of AA are as apparent here as with any PC game we have seen in the past. 

1920x1200 1xAA	1920x1200 4xAA

Here is another cut out from the images above: take a look at the edges of the "bone" on the base and on the spawning pool, etc.

1920x1200 1xAA	1920x1200 4xAA

And once again, a zoomed in look at the same image showing the visual benefits of anti-aliasing on StarCraft II.

So we know AA looks nice, but how is it affecting performance on our NVIDIA graphics cards?  In most cases, using in-game AA is beneficial from a performance perspective as the developer has the best knowledge on what SHOULD be anti-aliased and how it should be done.  But since Blizzard has left that feature out and NVIDIA is having to brute-force it, we expect AA performance hits to be more noticeable. 

At 1920x1200 the GTX 480 hardly sees a drop at all since the performance without AA was still being CPU limited to a certain degree.  The move to 4xAA on the GTX 460 1GB costs about 31% of our performance but the drop on the GTX 260 is HUGE!  More than half the performance is lost when enabling AA with the older GT200-based architecture card so if nothing else this should show us improvements in design.

At 2560x1600 performance drops with AA are again pretty substantial with about a 50% drop seen on both the GTX 480 and the GTX 460.  The GTX 260 sees about a 60% decrease in average frame rate. 

While AA performance hits are higher than we would like, because StarCraft II appears to be easier on your gaming rig than you might have expected, the GTX 460 1GB card looks more than capable of running at 1920x1200 with 4xAA enabled while the GTX 480 runs just fine at 2560x1600 with the same settings.

UPDATE 8/2/10 - Make sure you check the next page for updated ATI / antialiasing information.