By now, you probably are aware of the official unveiling of Apple’s iPhone software development kit (SDK) last week. Developers likely will be interested in the announcement of the iTunes App Store, where third-party developers can publish their applications for $99. A whopping 30 percent of this amount will go to Apple, though there will be no fees if you provide your application for free.By right, we should all have been able to go back to our normal lives and live happily ever after. Unfortunately, that is not to be. The folks over at TechCrunch have uncovered an ominous limitation in the SDK that was not initially apparent. The restriction is that only one application is allowed to run at a time. For example, you won’t be able to minimize an instant messaging application while you browse the web. Nor will you be able to run a stock monitoring program in the background to alert you of certain events. In both the above examples, the applications will be shut down when you switch out to do something else–even if it’s for an incoming phone call.