The EXT4 file-system with the Linuux 3.5 kernel will now support CRC32 check-sums on the meta-data fields. This work was done by Darrick J Wong to further improve the reliability of the EXT4 file-system. The EXT4 on-disk layout has changed to support the extended meta-data check-summing.
Aside from this new feature, there's the usual list of bug-fixes and clean-ups.
The EXT4 Linux 3.5 pull request can be viewed at LKML.org.