I've noticed over the past year that a Google search for almost any medical term will bury the wikipedia article on the third or fourth page of search results. The first three pages are all sites with extremely watered-down content and little to none of the cross-referencing links that make wikipedia a good exploratory tool (and a natural fit to PageRank).

Google has obviously decided that anyone searching for a medical term should only be shown pages that are equivalent to what a doctor would tell a scared patient in the first three minutes after delivering a diagnosis. Sure, those WebMD pages are probably going to be a bit more accurate than the wikipedia article, but largely because they're saying much less and have fewer opportunities to be mistaken. It feels rather condescending and patronizing.