Since announcing the sale earlier this week, Cambridge has gotten e-mails from current Top-Tens users wondering what impact his departure will have. "The app will work and update in the same way," Cambridge said. "I'm actually including all the back-end server side code in the auction, too, so end users won't notice a thing."

Don't assume Cambridge's departure means he's giving up on iPhone development. He's got a second app in the works that may be put on hold during his sabbatical. And, should the rumored Apple tablet appear, Cambridge has an app planned there as well.

"There's definitely a future in [developing for the iPhone]," he said. "With the right app, a decent marketing strategy, and a bit of luck, you can make a tidy amount from app sales."

That said, Cambridge would welcome changes at the App Store that would help programmers get the word out about their products. "At the moment, it's too difficult to find the genuinely useful apps that we know are there," he said. "If your app is featured on the front page of iTunes, then you're golden. You'll get lots of sales. However, if you're relegated to the depths of the store, your app will only sell in small numbers no matter how good it is." Apple's move last week to to their app descriptions was a step in the right direction, Cambridge says.

Still, Cambridge has one piece of advice or whoever winds up buying Top-Tens: market the app aggressively. "Like many devs, I thought that I could develop the app, get it on the store, and then sit back, and see the money come rolling in," Cambridge said. "Well, it's not quite that easy. You need to be able to market the app in many different ways."