Turns out that fellow was Brandon Sanderson, by far the most famous and successful author participating in the event. It was around the time he published his first Wheel of Time book. Everyone around me knew who he was and they were all starstruck, and horrified that I was so oblivious. I felt silly for failing to recognize him, but he was totally cool about it. He was gracious and kind, and very supportive of this small-time author. In spite of his success, he was so down-to-Earth that his advice is probably worth heeding.