A new trend I've noticed recently is for very large sites to incorporate wikipedia in their own results eg
bing: http://www.bing.com/reference/semhtml/Zeus
and orange: Zeus - Encyclopédie par wikipédia - Orange
rather than link out to wikipedia
orange is interesting because they have also incorporated ads in the text

do you think this serves a useful function for content creation? if not why would these companies be doing it?

also do you think they have downloaded the whole of wikipedia or do it page by page 'on-the-fly" somehow with cURL etc?