2.6.27.31-2 is up for both arches and _should_ fully support ext4 filesystem. So far I couldn't reboot my ext4 system, because it's busy with uploading other stuff for some hours.
Though I don't expect any trouble try it only with non critical ext4 root filesystem partitions. You've been warned. When we can canfirm this kernel well booting also into ext4 it's a major step to get real "fallback" state. -Andy
