Paul Kedrosky posts a list of things he's changed his mind about this year. Did you change your mind about anything this year?
I agree with several of his points: too big to fail, ignorance, blogs, AM radio, Hedge funds, Buffett, This time it is different, and oil.
While I'm not convinced that phones do not require keyboards, I've certainly softened on that point. My wife's new iPhone has my jealous of certain features, but I still love the easy one handed navigation of my Treo.
There is one recurring category that I found interesting: 'It works, until it doesn't'. He cited Technical Analysis and Wholesale funding model. I think this is an interesting idea in the broader context. There are a lot of 'things' that work, and work well, for a fixed period of time. Then something changes and they stop working. It is easy to get caught in that trap and not have the proper hedges in place (whether financial hedges or life hedges).
I'll take this as a lesson for 2009: There are a lot of things that work, until they don't.