
In the latest development snapshot of the upcoming Fedora 11 system, ext4 is already the default file system. There is also an experimental support for btrfs file system.
The Fedora Engineering Steering Committee (FESCo) has made the decision to make the ext4 the default file system after a debate on IRC. It has been decided, however, that if users encounter big problems with the new file system, Fedora will switch back to the popular ext3. In comparison, in the Ubuntu upcoming version 9.04, ext3 will still be the default file system and ext4 will remain as one of the available options.