Your user's brain wants a conversation! is a great bit by Kathy Sierra about the way that people pay more attention to and are more engaged by a conversational style than a lecture style. That's probably why blogs will suck me in and formal sites don't work as well.
It also explains why my preferred teaching and learning style is more informal. I think that it's a lot more fun to know what needs to be covered and learned and let it come out as you interact and share...I don't want to do things the same way every time.
It's all about conversations... that's probably why Hugh Macleod pointed it out.