I was not able to go to SIGGRAPH 2013 held recently (July 21-25) at the Anaheim Convention Center but did come across some useful information on-line.
Here are a couple of interesting preview videos
Emerging Technologies
(link: http://youtu.be/wle0bsog4iE )
Technical Papers Preview
(link: http://youtu.be/JAFhkdGtHck )
Other related videos can be found on the ACM SIGGRAPH YouTube Channel at
http://www.youtube.com/user/ACMSIGGRAPH
Other useful information is available from the SIGGRAPH web-site at