Hmm, I'm also experiencing segfaults on Arch x64 with Xorg 1.7.1 and nvidia 190.42, but with a very specific repro in my case.
I'm having a separate X screen setup with three screens (two screens - "left" and "middle" - on a 260 GTX and one screen - "right" - on a 8800 GTS). X starts up alright and moving the pointer between the "middle" and "right" screens works fine. But when moving the pointer between the "left" and "middle" screens (both on the 260 GTX), the pointer starts jumping between them like crazy, hundereds of similar Xorg log messages are written and eventually X will segfault. Here's the full log: