Personally I think some branding ala the Canonical standards is needed for the header to ensure users realise it is an officially supported Ubuntu site. However, I also think keeping it clean and simple like now is very very important because the basic stack overflow/exchange schemes are part of theretheir success.
Therefore I would suggest the Logo strip be used, although I have to say I quite like the current light blue sketched logo!
How about half way between the two?
