I'm a confirmed Ubuntu fan, but I'd be remiss if I didn't mention the release of Fedora 9 this morning. Fedora is the community-maintained Linux distribution that's the foundation for Red Hat Enterprise Linux (RHEL), the leading commercial version of the open source OS. No surprise, then, that it has a tremendous following.
You can think of Fedora as a testing-ground for RHEL; it's where you can find the latest cutting-edge features before they make their way out to the officially-supported distribution. That means it's really best suited for hobbyists, but it's also a good way to get the jump on the best that Linux has to offer.
The biggest change for this release is the inclusion of KDE 4, the most recent edition of the desktop software that powers Fedora. (Ubuntu, on the other hand, uses the competing Gnome by default.) KDE 4 brings new icons and changes under the hood that should make Fedora run faster and use less memory than earlier versions.
Fedora also now joins Ubuntu in shipping Firefox 3, which is still currently in beta -- so be prepared for some plug-in difficulties until third-party developers get their add-ons up to speed.
Other changes include support for the new ext4 filesystem, the ability to resize Linux and Windows partitions at install time, built-in support for encrypted filesystems, and improvements to how Fedora handles Xen virtual machines -- not to mention the usual host of bugfixes. For a visual tour of the new release, check out the official slideshows.
You can download Fedora 9 from one of the official servers now. Torrent files are available in addition to the regular disc images; or -- in another change for this release -- you can use Jigdo, a distribution system that helps speed up large downloads by breaking them into smaller chunks (somewhat like BitTorrent).