If you are going to watch the Olympics, SLRs are not permitted to be brought into the venues unless you are an accreditted photographer. Go to this link to check details.
http://beijing2008.popphoto.com/2008/07/slr-cameras-onl.html?cid=10
http://beijing2008.popphoto.com/2008/07/slr-cameras-onl.html?cid=10