You can't rebrand what never was properly branded.
Let me say it again:
Wikimedia is a Great Brand, the problem is that it was never promoted properly. In fact, the brand / logo is hidden at the bottom of the footer in every page!
I'm still waiting for your feedback in my ideas for the Wikimedia brand: http://lists.wikimedia.org/pipermail/foundation-l/2010-December/063014.html
-- Fajro