Went to the morning Athletics this morning, and as Dave says, what a great atmosphere. No doubt helped have Christine Ohuruogu, Dai Greene and of course Jessica Ennis amongst other Brits competing.
Camera wise I opted to leave the DSLR as home and we took compacts. Saw plenty of people with DSLRS, 4/3rds and Bridge cameras, did not see anyone with 'long lenses' or Canon's white lenses, but plenty with 24/70 type lenses. Security did not seem fussed and I was regretting not taking the DSLR a little and my 70/200 with extender. That said it probably meant I enjoyed the day a little more and did not worry about taking pictures all day.