There are many ways in which communication fails. Very often, this is because the writer (or speaker) forgets to take the audience into account. This is becoming increasingly clear in English 408A, the course on Media Writing that I'm taking this term. The current chapter we're discussing is Copywriting and Advertising. Batty and Cain have a lot to say about this, but the most important part of writing effective copy is to "always put the reader first" (p 159). I've attended lectures and presentations where the speaker is often from business management, speaking to technical developers, where much of the message is lost because they're using the specific jargon of the business environment. Those of us in the audience spend our time trying to figure out what euphemisms like business process excellence, and synergy really mean, rather than trying to follow the speaker's line of thought.
While Batty and Cain are talking about writing copy that sells products, the same theories apply to speeches where you want to influence others. I read a great blog post by John Jantsch, founder of Duct Tape Marketing, which suggests that great leadership has a strong storytelling component.
This is also one of the key points of Garr Reynolds, author of Presentation Zen. With a great story narrative, a speaker can weave together the elements that would have been dropped into technical bullet points. They will be more memorable if related with a good story.