Perhaps the guys with noticable stutter should post hardware specs? Perhaps even a dedicated thread for that. It would help to find a common denominator which could make it easier to resolve this issue as it's only some who is experiencing it.
I think we have multiple threads talking about stutter! I've posted in two of them, but here goes again.
Exteriors are fine, but certain interiors are definitely not smooth. FRAPS either reports decent FPS or takes a nose dive. One particular location I use for testing is
Orotheim, it's a small cave far west of Whiterun. Head there, and walk through the cave, looking left and right as you do so. I've tried this with and without mods and it's not smooth. I can get a steady 45 FPS on the infamous Whiterun viewpoint.
Specs:
Intel core i3 530 (non-OC)
Gigabyte GTX 460 1Gb (pre-OC)
8Gb DDR3
Windows 7 64 bit
1080p res
Beta nVidia drivers (the ones with the Skyrim optimisation)
Shadows - medium, 2xAA, everything else ultra. FXAA off. 16xAF and Performance AO via nVidia CC.
Running with 50 FPS cap via Inspector, and Triple Buffering via D3DO.