This Interesting article suggests President Obama is overly reliant on his teleprompt.

I'm not sure I'm really sold on the whole slideshare.net thing, unless they have synchronised audio with the slides. That said, there are some good ones and the best of them have something to teach about communication, if not presentation per se.  Like these three on Thirst and Globalisation and Presentations

Microsoft's Bill Gates and Apple's Steve Jobs are both legendary and iconic leaders, but their approach and philosophy to presentations couldn't be further apart. This great article from Garr Reynolds blog is a must read for anyone involved in designing or delivering presentations.