Arm architecture comes in three incompatible flavours. Hardware stays the same, but libc/linker etc are not compatible due to different calling convention.
Arm - OABI. The old one, and the one openmoko uses.
Arm - EABI. The new one. Should be slightly faster. Angstrom distribution uses this. (See http://www.angstrom-distribution.org/unstable/images/fic-gta01/20070524/ )
Arm - big endian.