Like Fedora, Debian has no proprietary software in it (yes, there is non-free, but that one is not part of the distribution).
1. You don't pay money for it. 2. The company behind it uses it to make money.
In Fedora's case, it's kind of a public beta of RHEL. In Ubuntu's case, Canonical provides support and professional services, although it's not profitable yet.
Also, Ubuntu comes by default with no non-free software. Although now I think there's an option in the installer to install MP3 and stuff that's restricted by patents. (not sure if it also installs non-free stuff like Flash).
So yeah, Ubuntu DOES come with non-free software by default, and the restricted repo is part of the default sources.list, to allow you to install even more non-free software easily.
By commercial, I meant they're (trying) to make money off of it, which they certainly do. There's a whole lot of things built around the distribution (Ubuntu One, support, etc) that in my reading, make the distribution commercial, or at least heavily commercially backed (as opposed to being community driven).
Of course, you have said that you meant commercial in that they're trying to make money off of it. Thanks for clarifying!
if you meant to say 'ubuntu is a proprietary distribution' then yes, that would be correct.