2D Competititon Rules (2011):

http://sourceforge.net/apps/mediawiki/sserver/index.php?title=RoboCup2011/Competition

3D Competititon Rules (2011):

http://hedayat.fedorapeople.org/misc/rc2011rules-v1.0.pdf

Please check the official wiki page for the most recent information:

http://wiki.robocup.org/wiki/Soccer_Simulation_League