I am not one to place tremendous importance on non-verbal communication and body language but it is undeniable that it has an impact on a presentation. Since the difference between winning a pitch and losing a pitch is a collection of small differences between agencies, we can't ignore subtleties like body language.
The following article in forbes.com does a nice job discussing body language.
Forbes article on body language
Ejnjoy...
Mark Schnurman
Co-founder
www.filamentinc.com