Like you said _k one wikipedia seems to be enough-"thank you google". But it won't cause us any trouble if there are two such things out there, maybe google could offer some thing more or different from wikipedia says, i think it might well enrich our project papers, for the better. if they contradict over something( though it hardly seems plausible they ever would), it would be a real tough call to decide.

Nice to know about KNOL. Wikipedia is my second favorite site, of course after crazyengineers. Google will have to struggle a lot to compete with wikipedia. Wikipedia is synonymous with encyclopedia. KNOL is bit different than wikipedia in that it will have articles authored by the contributor (selected by Google) and others contributors will need author's permission if they want to update the article.

In my opinion, Google should buy Wikipedia than trying to create another wikipedia.