I just searched something that (once again) gave me a Wikipedia instant answer.
And, once again, I was, for a split second, a bit confused about it : before clicking it, i'd like to know what the link is, but I really think the small "More on Wikipedia" is not clear enough.
Displaying a bigger logo would be great.
If you didn't want to do so to avoid publicity, I think it's a humble reason, but not really valid : the main concern should be the quality of information given to the end user. Thus, making sure he knows what he's clicking on seems to me to be a priority.
I want to know what I click on. And if I don't, I know that my parents won't ever know what they've clicked on (and I'm not even mentionning my grand-parents).
This is specially the case for Wikipedia, as it is widely used for Instant Answer, but it should apply to all instant answers that link to a specific service.
The final design should try to avoid the "advertising/publicity" style, but still it should put more emphasis on the origin of the information, and the direction of the link.
I hope this comment reaches somebody in charge somehow :)
(Sorry for the bad english, and as always, cheers and thanks for the good work on DDG).