The good folks at Canonical Ltd have announced the release of the newest version of Ubuntu Linux, 10.04 (LTS), code-named Lucid Lynx. This is a Long-Term Support [LTS] release, meaning that it will get software bug fixes and security updates for three years for the desktop edition, five years for the server edition. (There is also a Netbook Edition optimized for less powerful devices with smaller screens.) The ISO CD image can be downloaded from this page. As usual, the image is for a bootable “live CD”, so you can try out the system without installing anything to you PC’s hard disk. (Running from the CD, rather than from the hard disk, is generally slower, of course.) Once you have downloaded the CD image, just re-boot your computer from the CD.
The base system installation from the CD is simple, and gives you a system with a pretty complete set of basic software. It includes the OpenOffice.org office suite, the Firefox browser, and tools for E-mail, media players, photo editors, and many more. There is also a huge selection of free software available online via the Software Center.
It is also possible to buy Ubuntu CDs and DVDs directly from Canonical, from Amazon in the USA, and from various other suppliers.
The core Ubuntu distribution for desktops uses the GNOME graphical desktop. An official alternative version, Kubuntu, uses the KDE desktop, which may seem a bit more familiar to Windows users, and is available here. Particularly if you have older hardware, you might also be interested in Xubuntu, which uses the Xfce desktop, and requires less in the way of hardware resources. There are several other derivative versions for specific environments.
The Ubuntu Linux system, and the tools included with it, are all free software; you are not only allowed, but encouraged to share copies with your friends.
Update Thursday, 29 April, 17:35 EDT
I forgot to include a link to the Release Notes. Also, Ars Technica has a brief overview of the new release.