The latest Xorg is available in Hardy, Xorg 7.3, with an emphasis on better autoconfiguration with a minimal configuration file.
Linux kernel 2.6.24
Alpha 4 includes the 2.6.24-5.8 (2.6.24-rc8-based) kernel. This brings in significant enhancements and fixes that have been merged in the last few months into the mainline kernel. Among these is the introduction of dynticks support for amd64, bringing the same power savings already available on 32-bit systems to 64-bit laptops and desktops.
Alpha 4 includes [WWW] PulseAudio enabled by default. Some non-GNOME applications still need to be changed to output to pulse/esd by default and the volume control tools are still not integrated. [WWW] https://blueprints.launchpad.net/ubuntu ... dio-jumble
With Alpha 4, PolicyKit integration is visible in the administrative user interfaces. PolicyKit makes it possible to run administrative applications as a normal user, and have them get a particular set of extra privileges for certain operations, which allows fine-grained control over user permissions and enhances usability, as well as eliminating the security implications of running the whole application as root.
Firefox 3 Beta 2
The latest Firefox 3 beta is packaged in the repositories, bringing much better system integration including theming that mirrors the system such as icons and colours as well as having GTK2 form buttons and open dialog.
The GTK version of the popular Transmission BitTorrent client comes with Alpha 4. It's set to replace the Gnome BitTorrent downloader
The new Vinagre VNC client, which is set to replace xvnc4viewer, is installed by default in Alpha 4.
The Brasero CD/DVD burning application, which will complement the CD/DVD burning functions of Nautilus and replace the Serpentine audio CD burning utility, is installed by default in Alpha 4.
World Clock Applet
Integrating the features of the intlclock applet, the GNOME panel clock in Alpha 4 can display the time and weather in multiple locations.
Nautilus 2.21.6 in Alpha 4 uses GVFS, the virtual filesystem abstraction layer that's set to replace the aging GnomeVFS in GNOME 2.22, as its backend. In the near future, GVFS will make it possible to fix shortcomings of Nautilus such as the inability to restore files from trash, pause and undo file operations, and make it possible to escalate user privileges for certain operations using PolicyKit for authentication. It also brings a significant performance boost to many operations.
GNOME System Monitor
The GNOME System Monitor has a revamped "Resources" tab, with Cairo graphs that scroll and scale smoothly, and brand new widgets.
KVM is now officially maintained within in the Ubuntu kernel.
libvirt and virt-manager have been adapted to Ubuntu. They allow for easy guest creation and basic management out of the box. Virt-manager can be used to remotely administer guests on a remote server. They also work with XEN, even though it is not officially maintained.
The kernel also includes the virtio modifications which should greatly improve guest I/O access.