Raph Koster's stuff is boring as hell for me and I get nothing insightful or novel out of it. Having read his endless article series in Game Developer, it came as no surprise he would publish a title like "A Theory of Fun." Probably a decent guy, but I wouldn't hire him.
Dude, you were already voted down when I saw you. I ain't mad atcha. To prove it, I've upvoted you to cancel it out (you can't change existing votes on News.YC currently). And don't forget to visit begthequestion.info!
I believe he openly admitted his failures with Galaxies. A few of my former colleagues were quite close to the matter, and Galaxies was definitely an organization-wide failure. Raph was far removed from actual design duties when Galaxies started to croak.
Btw, Raph's got a Charles River-backed startup called Areae. It's doing some pretty cool things if you're interested in virtual worlding and web interaction.