Do you really know all about new features and improvements of Ubuntu Gutsy Gibbon? you can also see a tour of some of the features at the ubuntu wiki.
Compiz Fusion 0.5.2
GIMP 2.4.0 RC 3
Bulletproof X and Graphical configuration tool
Fast user switching
NTFS writing support
Encrypted hard disks
And here's some wiki-work-in-progress