It depends on what you're writing. If you're writing a fart app, development can take just a few weeks; most of the work would involve farting into a microphone. But if you're writing a video game, development can easily take a year or more. I've spent the last 10 months working on and off on an iPhone game, and you will not believe how much work it is to create a cool game. The coding part isn't that bad, it's the graphics part that's a kick in the ass. This game I'm writing consists of over 400+ different graphic files and it's still not done. And after you have the basic structure done, you have to build levels, add sound effects, minimize bugs, and whole host of other problems you run into just to make the game fun. While it's a ***** load of work to build a video game, it's still an incredible opportunity for small developers to even have a chance at competing with the big boys.