2.3 gingerbread - DroidX data encryption - which algorithm and how strong?

I have a follow-up to the question posted here. I recently got a 2.3 DroidX phone, and noticed that it as well has data encryption option. I pulled an SD card from device, and noticed that folder structure is intact. I tried reading file from the SD card, which was produced by a photo application, and it was unreadable, however the file itself contained some data which was not random, which to me indicated that not the whole file was AES'ed. I was also able to put an unencrypted file on SD card which was readable afterwards.

So, the question is: does anyone know what encryption methodology is being used here, what algorithms are in place, and how strong they are against experienced attacker?

EDIT: My friend got a droid2, which also runs gingerbread 2.3.3, and it has data encryption feature too. So... is data encryption an android feature or specific to Motorola devices?

Answer

Apparently, DroidX uses ecryptfs

Following are mount options on /data/data:

rw,nosuid,nodev,noatime,nodiratime,ecryptfs_sig=****************,

    ecryptfs_cipher=aes,ecryptfs_key_bytes=32,ecryptfs_passthrough

I would imagine this means that encryption key here is 32 bytes, which is 256 bits, which seems pretty good to me.