I usually find Gruber's tone to be arrogant and unnecessarily facetious. But I think his analogy is great.."This is like being a Rock and roll musician in the late sixties. This is like being a film maker in the seventies..."
I don't think that analogy really works because there is not much distinction between "Apple developers" and other developers. There is no barrier to start developing on Apple platforms and there probably won't be for the next big platform. Low barrier to entry is one key factor of a platform's success.
Sure there are barriers. A few that come to mind include the $99 per year Apple developer program fee, which is necessary to distribute apps, the Mac OS requirement, and the objective c hurdle. These may seem more like inconvenience barriers, but they do keep people away from the development pool.
I should probably clarify why I think the analogy works; It's an exciting time, it's changing rapidly, there's a lot of opportunity and developers are garnering a lot of focus from a lot of different areas.
