I posted something about the same subject in an earlier post...
basically, I had access to the 2005, 06-07, and 2008 Lecture Notes. The differences between the 2005 and the 2006-2007 are mostly organization (which actually helps quite a bit) and some new information put in and older information thrown away. There is no difference between the 2006-2007 and the 2008 as anthroguy correctly pointed out. I think there was one line in one of the 06-07 books that was omitted in the 2008, but that was it.