Published at LXer:
Ext4 is the evolution of the most used Linux filesystem, Ext3. In many ways, Ext4 is a deeper improvement over Ext3 than Ext3 was over Ext2. Ext3 was mostly about adding journaling to Ext2, but Ext4 modifies important data structures of the filesystem such as the ones destined to store the file data. The result is a filesystem with an improved design, better performance, reliability and features .
[I found the link to this article on LWN in the thread talking about the new 2.6.28 kernel
that Linus just released. Interesting stuff, 48bit addressing and a maximum filesystem size of 1 EB. 1 Exabyte? Wow! - Scott]