Mounting /dev/mmcblk0p1: Mounted on /mnt/mmc.
mmcblk0: mmc0:e7c8 SD512 500224KiB mmcblk0: p1
Searching for linux.boot.cfg: not found.
e2fsck 1.38 (30-Jun-2005)
fsck.ext2: while determining whether /mnt/mmc/AngstromOpie-t650.ext2 is mounted.
fsck.ext2: while trying to open /mnt/mmc/AngstromOpie-t650.ext2

The superblock could not be read or does not describe a correct ext2 filesystem. If the device is valid and it really contains an ext2 filesystem (and not swap or ufs or something is corrupt, you might try running e2fsk with an alternate superblock:
    e2fsk -b 8193 <device>

fsck.ext2: Segmentation fault
mount: Mounting /mnt/mmc/AngstromOpie-t650.ext2 on /newroot failed: No such file or directory
pivot_root: pivot_root: Device or resource busy
Please wait...
rm: applet not found
Passing control to Ansgtrom...
/linuxrc: exec: 90: /usr/sbin/chroot: not found
Kernel panic - not syncing: Attempted to kill init!