I have written about Andrea Mercado's tech training on this blog before and just really like her philosophy and style. She recently wrote about an email class she taught for beginners. She makes many great points and observations in the post, but the thing I am most struck by is her curiosity about the learners. I think that's the number one characteristic in a good technology trainer -- a genuine curiosity about the ways that people learn and try to make sense of things. Having solid technical knowledge, a great presentation style, etc... is all great, but I really do think that curiosity is the key.
I think a good trainer is not driven by getting through a certain amount of material, but is driven by constantly trying to gauge the experiences of each learner -- letting people make mistakes and figure out answers, helping people build their confidence with the computer. It's what makes training so challenging, but also what makes each class a unique and interesting experience.