I have a 6600GT card and have no problems with the sun not having its glare effect with AA on.
Ever since I started running in 1280x960 using the method found here..
http://www.communitymanuals.com/shii...lay_Resolution
I can run SH3 with 2x AA and still have the sun glare show up.Not sure what may have allowed the glare to be working but it is for me.
I was using diver version 81.89 but now am running beta 82.12's.