Sometimes I realize that multiple things I get irritated about are actually all tied together. This is one of those times.
Last week, I was at the Cisco Networkers conference in Los Angeles. While there, I noticed something that also happens at my job in training classes, seminars, town hall meetings, and so on: people who can't or won't escape work or play to simply do whatever they're there to do.
What I mean by this is that if a person gets sent to a class, they should pay attention to the teacher. If they are at a seminar, they should listen and take notes. When I see people typing away on laptops or PDAs (or talking on cell phones or pagers) for an entire hour or two, I have to wonder why they even bothered to show up. Understand that I'm talking here about people who are clearly and visibly not paying a bit of attention to whatever it is that's going on. They are wasting their own time, but worse, they are insulting the speaker(s) and perhaps distracting fellow attendees.
I say that if your job is so important that you really can't get away and focus, then don't leave in the first place.
I won't even get into vacations that feature email/pager/phone contact with the non-vacation world; I believe I've hit that before anyway.