Wikipedia Dominating Google Search

Recently I could notice the importance of Wikipedia in Google Search results. Wikipedia has high pagerank and most of its pages get listed on the Google SERPs. This is because of the ranking and relevance of the pages on Wikipedia.
But very often I get frustrated to see results like this and more over when there are millions of pages and domains on the world wide web, there should be some reason to list other websites on the top of Google SERPs. This happens only on Google and not other search engines like Yahoo, MSN or Ask.

Google search results are sorted giving importance to pagerank and other factors, but I have found many searches which lists pages from Wikipedia on the top, but when I go through other results which are much more relevant than the results on WikiPedia.

Is WikiPedia Dominating Google’s Algorithm, What do you say Matt?