http://engineyard.com/

Engine Yard uses Gentoo-based clusters for its Ruby on Rails deployment
service. There's a video about its use of Gentoo at
http://qualityhumans.com/images/tom_ezra_gentoo.mov. In it, they say
something like, "We're pretty convinced that all other distros are based
on Gentoo." But if you're putting it in the GWN, please listen to the
video yourself to confirm that.

Thanks,
Donnie