The EXT4 file-system pull request for the Linux 3.8 kernel
has been submitted and it's bringing fixes plus introduces two new features.
The two new features for Linux 3.8 with EXT4 are Inline Data and SEEK_HOLE/SEEK_DATA support. Ted Ts'o mentions that the inline data feature allows small files or directories to be stored within the in-inode extended attribute area. This inline data assumes that the file-system uses inodes that are 256 bytes or larger.
The SEEK_HOLE/SEEK_DATA support is enabled by the extent status tree patch-set and is infrastructure that will be used to further optimize the EXT4 file-system moving forward.
The other Linux 3.8 changes for this common file-system just comes down to clean-ups and bug-fixes. The merge can be found already in Torvalds' tree