I came across this article on bizjournals.com about a Louisville company, LG&E Energy, embracing the ITIL framework.  The outlines the initial steps LG&E took as well as some of the early benefits they received. 
 
One of the key notables is the method that LG&E imposed to ensure their "culture change" would be successful.  Each IT employee (230 of them) were required to take ITIL training to ensure that all were on the same level at the outset.  This is a very important step to outline the broad changes that implementing ITIL can have on an IT organization. 
 
One more good success story if you are justifying ITIL in your organization.