From the 'Source Based Distro' files:

Gentoo Linux is celebrating 10 years as a project this week with a special Gentoo Linux 10.0 LiveDVD.  The 10 year mark is a big milestone for what I personally view as, a very unique and interesting Linux distribution.

Instead of being binary based (like nearly every other distro), Gentoo's history is in the source. The benefits are that users get to actually compile applications (and the operating system itself) on their own machines.

In my own (limited) experiences with Gentoo over the years, it is the machine specific compilation that has always been very attractive. Instead of just x86 generic, you can compile for a specific computer to get a more optimized experience and better performance.

The problem with that method though is it can take a lot of time to actually get a Gentoo machine up and running. It once took me 3 days to get one test terminal built (yes it was an old CPU and should have had more memory).

Still, being able to have a CPU optimized OS is attractive to big IT vendors. It's something that at one point IBM found attractive too.