I'm glad it is not a personal mental deficiency - my inability to multi-task.
According to Brain Rules by John Medina, multi-tasking is a myth. (Great summary, including short video clips from accompanying DVD here at the Presentation Zen website. My personal copy of the book and DVD are on order!)
According to Medina, multitaskers take twice as long to accomplish things and have double the error rate. Check out the amusing video from YouTube (My trusted source of all things scientific.) and his Facebook! entry on the topic.
I thought of this yesterday when attending a presentation by Michael Wesch of The Machine is Using Us fame. (Great presenter and message, BTW). At the end of the keynote, I had an entire page of handwritten notes, which has become unusual for me. Why?
My laptop's battery was dead and the lecture hall had zero electrical outlets. I could not do my usual thing of checking e-mail, reading rss feeds, or Twittering and half attending to the lecture. Now Wesch's talk was probably interesting enough to suck my eyeballs away from the computer screen, but then again, maybe not.
One of the things that I seriously question is the conversation about "enhancing" presentations with live blogging, back-channel discussions, streaming on-screen chat, and other noxious goings-on. Are these things actually valuable or are we doing them because we're nerds and we can?