Yes, it might just be a problem of my 6600GT, which seem to be notorious for this shimmering. So whatever you do, provide it as an optional setting, nothing that should be enabled by default (of course it can be enabled if the majority thinks it looks better). Unfortunately nothing else besides the mip bias clamp option fixes the shimmering for me, no amount of AF and disabled optimizations helps.

I've seen much the same on a 6600gt, a 6800gt I own and a 8600gt a pal has - only one of the previous is on a reference PCB. At first I didn't notice that on my 6xxx cards as I had clamped the mip bias to start with in a generic AF-applying profile I had that applies to just about all 3d sims I play. Later when the "improve quality" thread by Jakg came up I noticed people talking about it being an issue with nvidia cards - sure enough, when I disabled clamping on my 6xxx cards it showed up.

I've fixed the reported issues and added support for anisotropic filtering (select 2x to 16x in Graphics Options).

Please read the help text on those screens for more explanation.

Mip bias is also separately adjustable for various categories of surfaces.

http://www.lfsforum.net/showthread.php?t=40303