Do you care about anti-aliasing? Do you dream of snuggling up to its sort of crisp edges and mild performance hit? Or are jaggies an acceptable compromise in the name of RAW INCREDIBLE SPEEDY SPEED? It's one of those things I find it increasingly hard to go without (though not as much as anisotropic filtering, missus) yet it's always the first thing to go if a game's not running so well on my ageing PC. Also, so many games don't include a decent/any option for it in their settings, requiring me to have a fiddle in driver settings with variable results. Both NVIDIA and AMD are trying to change that, with newer anti-aliasing tech and the option to force it on globally in driver settings.
(I'll probably get a bunch of stuff wrong here, but I am just trying to address the very broadest strokes. Dave Science I am not.)
FXAA is an NVIDIA-governed alternative that's been doing the rounds in some titles with broadly positive results. It can muster edge-smoothing that's not quite as nice as traditional MSAA but has only a fraction of the performance hit and fares better with transparent textures. The snarkier elements of the tech audience observe that FXAA is basically a post-processing blurring, but I've found it's a decent halfway-house in practice.
Those who demand the finest image quality will stick with the old ways, but rank and file PC gamers may be pleased to hear that NVIDIA have just introduced FXAA as a driver toggle for their legacy cards, not just their new GTX 680. While not all games will play nice with it, 'hundreds' apparently will, and without having to have it as an option in their own settings.
AMD cards don't officially support FXAA (apparently hacked drivers are available if you know where to look, and certainly Battlefield 3 was fiddled to offer it on AMD), having instead pushed their own alternative MLAA, or Morphological Antialiasing. Version 2.0 of that was recently released with the 12.3 and 12.4 beta Catalyst drivers, and apparently offers sharper image quality than both MLAAA 1 and FXAA.
So in theory no-one's losing out in this new anti-aliasing party, but as with so many things NVIDian and AMDian throughout history, technology - and with it PC games - is branching out in slightly separate directions that's going to complicate matters in all sorts of ways.
The new GeForce 301.24 beta drivers, plus a clutch of chest-thumping about what they offer (adapative V-sync and frame-rate limiting are the two other headline features) can be found here, while AMD Catalyst 12.3 is here or the 12.4 beta here.