Google's ranking of Wikipedia articles is due in large part to Wikipedia's great PageRank ranking. I don't think Google is giving Wikipedia any sort of singled-out treatment, Wikipedia just ranks highly on Google's relevance metrics.
The problem with Wikipedia is that many of their articles are poorly regurgitated versions of other source articles from the Web and that these source articles get no Google credit at all, even if they are linked from the Wikipedia articles, since Wikipedia uses no-follow links. Wikipedia ranks near the top in Google for almost any term for which it has an article, regardless of its quality.
I guess what works for some people doesn't work for others; most often when I'm looking for something I enjoy the wikipedia article on it and think that it's relevant. Also, a lot of times I don't actually go to google but type my query into the search bar (google is set as my default) so a search happens. It takes me to the first site, and most of the time it's wikipedia I want / get.