Check out this post over in the Creating Passionate Users blog for excellent presentation advice, including a new take on being passionate that bears repeating:
Care about the audience. Care about their time. Care about their attention. Care about what they probably paid in time and money to be there. Care because... that's the kind of person you are ; )
What a great way to focus on the audience instead of on your own nervousness, your message, how you will come across, what will happen if you mess up. As my friends are all too willing to point out, "Sometimes it's not all about YOU"! :-)
Another way to think about caring is to ask yourself, "If Joe Blow from the audience only walks away with one thing from this talk, what would that one thing need to be in order to make it worth it for him?"