Anyhow, I've resized a couple of the pictures so they show per-pixel detail reasonably well, and you can see them below. What you are seeing is ATI's 2X temporal AA mode, which looks effectively like 4X AA. (For an explanation of temporal AA, go to this page of our X800 review.)
Notice how, in the left pic, both near-horizontal and near-vertical edge jaggies are reasonably well smoothed out, as one might expect from a 4X mode rather than a 2X mode. The right pic is a close-up of the power node map in UT2004's Onslaught mode. The not-quite-45-degree red line stretching across the map doesn't have the stairstep breaks across it that it does with no AA or 2X AA, and the rest of the lines are antialiased, as well. These pictures don't quite do justice to temporal AA, but they should give you some sense of how effective it can be. Thumbnails below. Click for the full version.