Are you sure that you use geninitrd and mod-md.sh from svn trunk? Here with your mdadm --scan... output works fine:
geninitrd: Finding RAID details using mdadm for rootdev=/dev/md0p1
geninitrd: md: found rootdev=/dev/md0p1 on device /dev/md0 with devices list /dev/sda1 /dev/sdb1 /dev/sdc1
Are you sure that you use geninitrd and mod-md.sh from svn trunk? Here with your mdadm --scan... output works fine:
geninitrd: Finding RAID details using mdadm for rootdev=/dev/md0p1
geninitrd: md: found rootdev=/dev/md0p1 on device /dev/md0 with devices list /dev/sda1 /dev/sdb1 /dev/sdc1