The site uses a template from JoomlArt - JA Vauxite. They also use the JoomlaWorks "Frontpage Slideshow" to highlight the newest articles. This creates an appealing front page and fits nicely with the otherwise sober, elegant layout.
Linux.com also use the extension EventList to show upcoming events here. This makes for a clean overview of events at the site, and as far as I know, an easy way for the site managers to update the events list.
Additionally, the site uses the commercial extension myBlog for the Community blogs section.This gives the section a more blog-like feel than the rest of the site (with the use of avatars, social bookmarking buttons etc), and the system makes it even easier for the writers to contribute.
As a nice touch, I noticed that linux.com features Accessibility functions, which enhances the use of the site for people with eyesight problems.
Visit www.linux.com to see the site in action for yourself.
Congratulations to Linux.com - and the Joomla! Community on the choice of Joomla! CMS for this important site!