Since it came up in the toolchain meeting this morning, some links to issues people are having doing ARM scratchbox-style builds because of generic linux-user issues:
http://bugs.meego.com/show_bug.cgi?id=10529 # linux-user's mmap implementation isn't very smart https://bugs.launchpad.net/qemu/+bug/668799 # qemu locking issues which can cause build failures (sometimes)
-- PMM