www.acquia.com
Dries Buytaert, the founder of the Drupal open source content management system has co-founded a company to provide a set of support services aimed at the enterprise and business customers looking for a supported version of the tool. It appears to be based on the RedHat model that has proven to be viable in the Linux community.
You should take a look at the screencast on how to install and how the Acquia version is different from the community version.
Check it out.
Randale