Viking is directly available in a lot of distributions, and can be installed with the package manager.
Viking is packaged for Debian and available in official repositories - on Lenny stable and testing/unstable. Simply do:
apt-get install viking
For more information, take a look at Overview of viking source package.
To install Viking in Ubuntu, simply paste apt:viking in Firefox, or go to Applications - Add/Remove, search for viking, enable the checkbox and click Apply Changes. It'll then appear in Applications - Education.
You can get packages from the openSUSE Build Service project Application:Geo
Viking is available via Fedora base repository. Simply do:
yum install viking
For more information go to Package: viking Overview
An Ebuild file can be found for Viking on our SVN: Viking.ebuild (viking.svn.sourceforge.net)
A PKGBUILD file can be found for Viking in the Arch Linux User Repository (AUR): PKGBUILD
Viking is available in the official ports tree as astro/viking.
Viking is available as the OpenEmbedded bitbake recipe and may be cross-compiled for any supported platform.