Jon recently published a blog post stating that you’re free to create Ubuntu derivatives as long as you remove trademarks. I do not necessarily agree with this statement, primarily because of this clause in the IP rights policy :
The disk, CD, installer and system images, together with Ubuntu packages and binary files, are in many cases copyright of Canonical (which copyright may be distinct from the copyright in the individual components therein) and can only be used in accordance with the copyright licences therein and this IPRights Policy.
From what I understand, Canonical is asserting copyright over various binaries that are shipped on the ISO, and they’re totally in the clear to do so for any packages that end up on the ISO that are permissively licensed ( X11 for eg. ), because permissive licenses, unlike copyleft licenses, do not prohibit additional restrictions on top of the software. A reading of the GPL has the explicit statement :
4. You may not copy, modify, sublicense, or distribute the Program
except as expressly provided under this License. Any attempt
otherwise to copy, modify, sublicense or distribute the Program is
void, and will automatically terminate your rights under this License.
However, parties who have received copies, or rights, from you under
this License will not have their licenses terminated so long as such
parties remain in full compliance.
Whereas licenses such as the X11 license explicitly allow sub licensing :
… including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software …
Depending on the jurisdiction you live in, Canonical *can* claim copyrights over the binaries that are produced in the Ubuntu archive. This is something that multiple other parties such as the SF Conservancy, FSF as well as Bradley Kuhn have agreed on.
So once again, all of this is very much dependent on where you live and where your ISO’s are hosted. So if you’re distributing an Ubuntu derivative, I’d very much recommend talking to a professional lawyer who’d best be able to advise you about how the policy affects you in your jurisdiction. It may very well be that you require a license, or it may be that you don’t. I’m not a lawyer and AFAIK, neither is Jon.
Taken a bit more extreme, one could even argue that in order to be GPL compliant, derivatives should provide sources to all the packages that land on the ISO, and just passing off this responsibility to Canonical is a potential GPL violation.