Selling itself is a misnomer. Nothing "sells itself." Selling just means a combination of things you need to do communicate well to other people about what your service/product does, why it does it better than anything else, and how you're helping people solve a problem or gain some kind of entertainment or value. So selling could be in the form of a very well defined sales funnel (a la 37signals), writing/publishing content as a loss leader (a la 37signals), releasing open source content (a la 37signals), and ultimately building up a base of users/customers because you were able to get good at communicating with them. Or, even as Jason Fried has said (and I do agree) selling is almost like teaching others something. If you can teach well, you've got a shot at selling (and communicating well).
But yes, being able to "press the flesh" and meet face-to-face, do deals with large customers, sell custom contracts or whatever is also selling. It might be that kind of selling that the geeks often struggle with.