Please tag xz-4.999.9-0.1.beta.20091007git.fc12 for F12 beta. This changes the compression to produce the same output on big-endian and little-endian, which will make deltarpm reconstruction work regardless of the arch the package was built on.

I've installed the version and done a quick sanity check on x86_64 - it still compresses and decompresses fine. jwb tested on PPC, and it produced identical output to what I had on x86_64.