Scrum Guide update was recently released – http://www.scrum.org/news/2011/7/15/new-scrum-guide-released-2011.html
Ken Schwaber has done a short podcast together with the NYC Agile folks that describes the changes to the newest release of Scrum. Very clear explanation to what was changed and why it was changed.
I originally downloaded it originally from here and put on my website for future reference – www.agilemindstorm.com/books/agilenyc_episode28.m4a