Pushka mentioned (a lot of posts back) the time when no carry on was permitted at all. We flew out of Edinburgh the day after the Glasgow airport attack in 2007. Luckily we were only flying to Dublin but the only things we could carry on the plane were our passports and and I think (but don't quote me) wallets. From memory medication was OK as well but no mobile phones, cameras, handbags, backpacks at all. Consider it travelling light.
Have also had lots of carry on bag searches over the years - Paris CDG sticks in my mind as the queue was very long and there were about 6 or so officers at tables doing the search.
Cusco had a more hands on approach to screening as they hand searched all luggage before check in. You had to unlock it and explain what things were (e.g. what was in the bag? dirty clothes). It did slow check in down somewhat.