Judge Orinda Evans's decision consists of a 350 page brief which you can find here (PDF). It's far too long for even me to have read already, but the short answer is that Judge Evans found that the vast majority of the 99 examples listed in the original complaint were not in fact copyright infringement. The librarians were correct in believing that their activities were allowed by the fair use exception.
This decision affects far more than just what a few librarians were doing. The fair use exceptions debated in the lawsuit owe their existence more to court decisions and legal theory than they do to the laws which have been passed by Congress. Had this lawsuit gone the way the publishers wanted, it would likely have affected the very concept of fair use. At the least, institutions everywhere would have been forced to reevaluate their activities. This lawsuit was so far ranging that I think it would not have been out of the question for libraries to go so far as to remove photocopiers from public access (out of fear of liability).
Now, I've been following the case but I have not posted on it. This case was complex enough that I think it requires a legal scholar to fully explain it, so I will direct you to experts like the blog Scholarly Communications @ Duke.
But this might be new to some, so here is a list of past coverage that I found useful. Note that it is in chronological order.
- Publishers Sue Georgia State on Digital Reading Matter (New York Times) - 16 April 2008
- Going forward with Georgia State lawsuit (Scholarly Communications @ Duke) - 1 October 2010
- A nightmare scenario for higher education (Scholarly Communications @ Duke) - 13 May 2011
- What's at Stake in the Georgia State Copyright Case (The Chronicle of Higher Education) - 30 May 2011
- Georgia State update (Copyright Librarian) - 9 June 2011
- The GSU decision — not an easy road for anyone (Scholarly Communications @ Duke) - 12 May 2012