Anne Mini recently did a series on how to construct proper author bios (Parts 1, 2, 3, 4, 5), and this inspired me to redo my own author bio. The old version was much longer, and in some senses more informative, but the problem with it was that it was just too long. There was just too much information that I was trying to convey at once, so the important points were lost in the shuffle. It was really styled more like an encyclopedia entry than a marketing tool, anyway, so I doubt it would have been very effective with professional readers.
As Anne points out, one of the primary purposes of the author bio is to make the author sound interesting. I think my new version does that a lot better (and more concisely) than the old version did. For those of you with websites and/or blogs -- do you have an author bio online, yet? It might be a good thing to do, both as a great thing to have on hand for when agents request it, and to have readily available online in case someone from the industry stops by (you never know, right?).
If you post one, drop me a comment and let me know; I always like finding out more about the people who stop by my blog!