On a new installation of Ubuntu 9.10, the system uses the Ext4 file system, the GNOME 2.28 desktop environment and the GRUB 2 boot manager, by default. However, it should be noted that neither of these is implemented if you update from Ubuntu 9.04 (Jaunty Jackalope). The Kernel has been updated to kernel 2.6.31 and now offers kernel-based mode setting, which should make the graphics issues in Ubuntu 9.04 a thing of the past. DeviceKit and udev have replaced HAL as the system’s hardware interface. The boot system has largely been transitioned to Upstart. The AppArmor security extension offers protective profiles for a range of applications.
On the desktop, “Add/Remove” on the Ubuntu application menu has been replacing by the new Ubuntu Software Centre, designed to simplify adding applications with a friendlier interface for package management. Ubuntu One, the Cloud backup and sharing system, is also included which installs CouchDB in the background to synchronise local data with a server on the network. Empathy has replaced Pidgin as the default instant messaging client.
For servers, Ubuntu 9.10 has versions that are designed to run on the Ubuntu Enterprise Cloud (UEC) or on Amazon’s EC2 cloud. UEC is based on Eucalyptus, an API compatible, open source implementation, of Amazon’s EC2 cloud system.
I haven’t yet tried Ubuntu 9.10 as I am still running Ubuntu 9.04, but intend to do so soon and will write a post about my experiences when I have done so.