Speaking in front of people was never a problem for me. I know many people have a fear of doing so. Sure, when I have a full room or even a small room my pulse races and I get some of those butterfly's.
In High School I did the Debate and Forensic thing which got me started into looking at what makes a good presentation. Then in college I took classes in which I could do more presenting and get feedback.
Finally I think the best training was at Radioshack where I spent pretty much every day presenting technology to people and explaining the benefits to them.
Building a process of presenting and tuning this process has been very helpful for me. Parts of this process include entertaining people adding value and leaving them with little nuggets that can be remembered.