Canonical gave permission for Stack Overflow/Ask Ubuntu to use the Ubuntu trademark and logo. A Canonical employee also assisted in the site's new design to help meet the [Ubuntu Brand Guidlines][1].

Beyond that the site is not officially endorsed by or related to Canonical. 

(Note: There are Canonical employees that are members of the Ask Ubuntu community.)


  [1]: http://design.canonical.com/the-toolkit/ubuntu-brand-guidelines/