Ubuntu has a new trademark policy. Permission must be granted to use Ubuntu trademarks, including projects like Fluxbuntu. Read more on the trademark policy page and Mark Suttleworth’s blog.
Ubuntu’s trademark policy opens by stating what’s covered by the policy. “Canonical owns a number of trademarks and these include UBUNTU, KUBUNTU, EDUBUNTU, and XUBUNTU. The trademarks are registered in both word and logo form. Any mark ending with the letters UBUNTU or BUNTU is sufficiently similar to one or more of the trademarks that permission will be needed in order to use it.”
Non-profit groups using Ubuntu for open-source community purposes are exempted from this requirement. On the other hand, a non-profit group that takes Ubuntu’s code, makes minor changes to it and then releases it falls into a different category.