Comment 22 for bug 130836

I'd argue it's against point 5 and/or 6 of DFSG:

http://www.debian.org/social_contract

You can't restrict the purpose for which it's used. By your license,
ihateopendoc.org (if there is such a thing) couldn't use the icons and that's
a restriction on the type of use.

The simplest thing to do is just to license it under the Apache Software
Foundation license. Then there's no possible issue.

Also, your web page should say the icons are copyright you and not trademark
unless you've actually registered trademarks and are legally entitled to the
mark.