In a recent webinar, Tim P. asked, "Surely if your content is compelling enough you CAN grab 100% of your listener's attention?"
Tim, I LOVE the question.
Here's my experience... some will no matter what you do, and some won't...no matter what you do.
I recently got an email from an instructional designer from a major university in the U.S. who said, "Wow! I couldn't attend the live event so I just watched the recording..and you kept my attention all the way through! That's hard to do!"
As much as I'd like to pat my own back (I won't - it'd give me arm cramps), the reality is that audiences are multitasking even in in-person presentations. Blackberries, iPhones, web connections everywhere...you get the idea.
I think what we should do is assume we have partial attention and plan/design/deliver for it.
CAN it be done? Yes.
Can it be done every time with every member of your audience?
Assume partial attention.