It seems to be a fundamental aspect of the world that, whatever you do for a living, you have to do that and be a salesman. When I say selling, I don't mean the purely business related contract-signing, accounting and banking aspect of sales, I mean really 'Selling yourself'. Marketing, if you will. The bit of the process that involves firm handshakes, giving presentations at conferences, reminding people at every opportunity that you are selling something they need. Even if they don't know they need it. Even if they don't need it.
You could be the greatest web developer known to the history of the interweb creating progressively-enhanced, backwards-compatible masterpieces of semantic mark-up which not only push the boundaries in the latest Webkit nightlies but still fly pixel-perfect in IE6 and you still wouldn't be able to run your own agency without selling your services.
Your iPhone app might be 'The Greatest App Ever Invented' combining the power of Google, the ease of use of Twitter and the graphics of Epic Citadel. It might prove the Riemann Hypothesis, remind you of birthdays, cure cancer all while showing pictures of cats falling asleep but unless somebody actually knows it exists, it's no more useful than those apps that play the noises of bodily functions while simultanesouly being less succesful. By putting it in the iTunes Store you are technically selling it but you're not 'selling it'.
The same situation applies in every industry – writing books, making sandwiches, playing piano, juggling. Unless you are lucky enough to be 'discovered' by someone with the ability to sell but without anything to actually sell, there is no difference between you and everybody else in your field. Despite what you may have learnt in school, you do not get to the top of the class by being the smartest. You get to the top by putting your hand up when the teacher asks a question.
A few months back I saw an article entitled 'Talent does not go unrewarded'. I've seen too many shy, socially awkward developers who won't progress past the minimum acceptable salary for their job title to believe this. More accurately, I'd say 'Talent does not go unrecognised'. They don't get rewarded for their technical wizardry, they get rewarded for convincing their bosses they're worth more than they're currently being paid. For selling themselves.
Evan Williams' recent step down from CEO of Twitter to focus on product develpment strikes me as the developer's ideal – all the success and reward (financial and kudos) without the daily requirement to constantly sell. Of course, Twitter wouldn't have gotten to where it is if he hadn't been able to take on that role along the way.