README:

Scripts to build x264 enabled ffmpeg for iOS 5 (Xcode 4.2 default directory structure)

gas-preprocessor.pl
Copy into your /usr/local/bin directory (or /usr/bin if the former is not in your path).  The latest can be found at https://github.com/yuvi/gas-preprocessor, but this version works fine.

build_x264 (use first)
Uses Git to retrieve the latest versions of the x264 source code and initiate a build on them. Make sure you can use git. Creates two versions then lipo's them together.  Use the library packaged in x264-uarch

build_ffmpeg_x264.sh (second)
Uses Git to retrieve the latest version of ffmpeg and do a build on it including the x264 library.  It also turns on the h264 encoders/decoders. Builds versions for armv6 and armv7 and lipo's them together into ./build.universal.  The header files are in ./installed/include