Rob really nailed it with this blog entry. He's talking about how and why great developers get booted up into the management track and why that's a really dumb way to treat your tech talent, not to mention just plain bad business.
You can read about the same idea on Wikipedia under the Peter Principle article. It basically says that we are promoted to our level of incompetence, then we get trapped there. Very few people have the insight or courage to bail from the bad position and get back to what they love and do well.