Maybe it's just me, but if I'm trying to explain an idea to someone and they're busy tapping away at their keyboard it really bugs me. Are they making notes on what I'm saying? Or are they checking in on HN? Ditto for the rare occasion when I'm in a dull meeting with a laptop - it's really difficult for me not to browse my inbox should a message show up, and then I think about a reply, and then I'm lost...
I find physical handwritten notes in a meeting is less distracting for both the speaker and the listener.