I was reading an article about how easy it was to spam "buy viagra" on Google and went ahead and looked at some of the results in the engine. Take a look at
buy viagra - edu, edu, edu. And every page is is a solo spam post with no responses... not even a pharmacy. Interesting.
If you search for just "viagra," you'll see all kinds of URL-shortening services like Tiny URL. The pages themselves don't have anything of or related to Viagra. I would think that Google wouldn't open themselves to people just spamming .edu message boards for rank.