Good post. It's a developer-specific flavor of Imposter Syndrome that I've struggled with too. Must learn all the frameworks! Now! And my designer side wants to master ever style I see on Dribbble until Photoshop stands up and starts clapping.

A book that helped me overcome it is called Mindset, written by the psychology researcher Carol Dweck. I can't recommend it highly enough. Apparently the problem gets worse as you gain skills, not better, if you don't consciously take steps to counter it.

I was just chatting with a friend this weekend that I also recommended the book to because he identified Imposter Syndrone as his major obstacle in life, even though he's highly accomplished and his blog is constantly on HN. Talking to him made me realize that it not only affects more people than I realize but that it probably also affects generalists more than specialists, since being T-shaped means by definition that you can only pick a few areas to go deep.