What I did: downloaded the Stanford courses on iPhone development, spent two weeks working (really, playing) my ass off. Spent the next four weeks making my first app (http://colorstreamapp.com/). Was excited to make millions on release!!!

Made nothing. Worked harder, made some. Worked more, made more. Now it's a decent income stream and I've gone from a nobody to a less-nobody.

Age is less of a barrier every year. Get started ASAP. As pg often says, if you're so passionate about something, why aren't you working on it RIGHT NOW?

Good luck!