There's plenty of stuff been written on these very forums concerning AMDs 3D (HD3D as it's now been labelled)
solution just do a search.
I think the main bugbear is you still have to buy 3rd party drivers to get it working, why AMD can't sort their own 3D drivers out for their own cards is beyond me?
Once you've bought the drivers you then have to source the 3D glasses, again these will have to be third party items as you won't find dedicated AMD 3D glasses to buy at this moment in time.
So after paying for your 3D drivers and sourcing some compatible glasses you'll then need to find a compatible monitor to play your 3D games on,
apparently not all 120Hz monitors work with it atm, in fact judging by
this list there's a grand total of 3!
Nvidias 3D vision on the other hand is pretty flawless, setup is a breeze, most games work really well with it including lots of old titles,
there's plenty of new titles coming out that are 3D vision ready, and it will work on all existing 120Hz monitors, basically it's all integrated beautifully.
So to conclude, at the moment there really is no comparison between Nvidia and AMD when it comes to gaming in 3D,
hopefully AMD will catch up enough to give people more of a choice but until that day comes Nvidia have 3D sewn up.
Some more reading for you
here