Respect should be a given
Leon is talking about the way Microsoft Regional Events are handled, interesting reading. We don't have those in Israel, and in the last Microsoft conference ( I took part in it ), we built our own talks, from our own experiences.
When you are thinking about investing the time in coming to an event, there is nothing quite as annoying by being shown something from marketing. That is a waste of time for most people.
The Israeli mind-set is such that 2,000 people can just leave the TechEd keynote talk if they feel that it is wasting their time. Marketing is a waste of time and it shows that your product is (a) lacking in concrete exciting features (b) you are not respecting the intelligence of the audience.