At a 5-day series of presentations, I was asked to arrive on day 4. My presentation was last for that day. I turned up early that morning and sat in the front, occasionally glancing backwards to gauge the audience. They seemed thoughtful and attentive, as their laptops weren't being used for goofing off. Someone else turned up after me, so I moved to the back of the room. It was then I noticed that the audience's laptops were being reformatted and reinstalled. One of the audience members quietly and sadly confessed they had run out of other tasks. I excused myself out of that meeting, cut down my presentation from 3 hours to 15 minutes, came back in when I was scheduled, did my 15 and told them to look for the full presentation in their e-mail, then gave them the rest of the day off.
My drinks that night were all paid for.
This is why I have to thank the fact that I have very few meetings and essentially never have to do presentations... I feel for dilbert... must suck having to spend hours writing up all the meeting materials to basically have them wasted near enough every meeting.