I freshened up our copy of libx264 earlier today in prep for that long-forthcoming snapshot build.
It seems that x264 no longer builds right with nasm in x86 -- it fails on the CABAC assembly code.
You need to install yasm to build it. Which I think means using fink, darwinports, or compiling it from source: http://www.tortall.net/projects/yasm/re ... 6.2.tar.gz
Again, sorry. It wasn't an obvious problem. I'm still on PowerPC Macs, where it builds fine, and I didn't realize there would be collateral damage on the Intel side of things.
As eddyg has pointed out, it should probably be made part of the configure check for x86 boxes. Maybe even bundle a Mac binary of it like we do with jam, since the yasm project doesn't even offer an official Mac build

If this is a pain in the ass for another people, I'll just revert the commit and we'll go back to our old out of date x264 with its old out of date VAQ.