One presenter spoke in a monotone and was consequently not engaging. Another presenter rushed through everything, going too quickly for the audience to keep up or process the information that was being thrown at us. The final team of presenters ummed and liked their way through everything.
A couple of pointers for presenting seem to be in order. Of course, you could always turn to the experts for help (I recommend @pistachio). However, there are a few simple things you can do to prepare to speak in front of people, or a few things to keep in mind.
First, don't freak out. Do whatever you need to do to not freak out. Normally that means:
Prepare just enough--too much scripting makes you sound like a robot, not enough pre-planning makes you sound like an angsty teenager trying to ask someone to the prom.
Speak clearly, annunciate; speak loudly enough for the back of the room to hear you. Speak and believe what you're saying.
Look for ways to engage. Tell a story. Make eye contact with members of your audience.
Finally, let's reiterate the most important one: don't freak out. If you're nervous, the audience will feel it. Be confident and comfortable.
Nobody is perfect. Admittedly, I'm not a fan of public speaking. It makes me nervous. But last year at Podcamp 2, Laura Fitton (aka Pistachio) spoke on speaking. The take away was simple: BE YOURSELF.