Pretty cool, but I wonder how many iPhones are actually jailbroken.

Looks like the jailbroken iPhone app scene is about to get seriously interesting -- not only is Cydia is going from package repository to full-fledged app store, a new jailbreaking service called Rock Your Phone is set to launch, and there's a planned adults-only app store. Details are light on the others, but the Cydia Store will offer developers a distribution alternative to Apple's official App Store unencumbered by that pesky SDK agreement and approval process -- are you ready for commercial fart apps with direct hardware access? Of course, users will have to jailbreak their phones 

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http://www.engadget.com/2009/03/06/cydia-developer-planning-independent-iphone-app-store-others-pl/