Bill Slawski recently did a great post about University SPAM. He tried some smart queries that exposed how it is taking place:
As you can see if you look at these queries, there is a lot of spam happening on university sites. What happens is that they have message boards that have been up on them for a long period of time, and people are manipulating these boards to their advantage.
There are so many of these opportunities out there, you can see why people keep pursuing them. But you can rest assured that this loophole will be closed shortly by the search engines, if they haven’t been already. As soon as the word gets out on these tricks in a broad public way, the clock starts ticking on their value being eliminated.