It's been an interesting 6 months watching Ubuntu 10.04 evolve from Karmic to what it is today. From a new theme that also includes a small but rather radical change to the introduction of nouveau as the default open source driver for nVidia hardware to the expansion of Ubuntu One with new services like file sync and music store, just about everything got a good shaking up during this LTS cycle. Quite frankly I'd say it looked more like the post-LTS cycle.
There are, of course, the usual updates to the core packages in the system. The most visible one, as always, is the GNOME desktop. The only conservative part of this cycle as I see it would be the choice of not going for the newer 2.6.33 kernel but instead focusing on stabilising the 2.6.32 kernel.
As a point of interest, HAL finally gets removed from the system. This component has been around for quite a few years, serving to make the Linux desktop experience much more dynamic than it used to be. Now, it's bloated with features it was never meant to support. Various components designed specifically for the tasks HAL was never meant for have matured enough to take over. And so they have. With HAL gone, Ubuntu should boot just that little bit faster for its users.
Perhaps another big change aside from the eye grabbing theme would be the new indicator applet. For several releases now, the Ubuntu developers have been replacing the standard applets with new indicators. A lot of users have complained about the inconsistent look and feel of the system tray area, so the Ubuntu developers have been slowly moving towards solving this issue. The system clock applet, volume control, network manager, all finally come under a single unifying applet providing a more consistent user experience.
In keeping with Ubuntu's open source roots, of course, the new indicators can be easily removed which would revert the system tray to its old behaviour. Ubuntu's focus are end users who don't know nor care to know the plumbing so long as everything just works. More advanced users get a simple default setup that just works and can tweak it from there.
Overall, this LTS has shaped up to be one that's focused mainly on social integration. Gwibber gets included by default, providing access to various social networks right from the comforts of your desktop. It's a nice touch for the more social types among Ubuntu users.