Five fab apps for iPhone OS 3.0 and the new 3GS

Apple Inc. has an interesting pie-slicing problem coming as far as developers of iPhone (and iPod Touch) applications are concerned. All of those first- and second-generation iPhones run the same operating system -- the just-released iPhone OS 3.0 -- as the new 3GS model. But the latter includes new hardware such as a magnetometer, a faster CPU and faster GPU, as well as more memory. If developers build shiny new apps with only those features in mind, they'll limit their market. What to do?So far, most developers seem to be focused mainly on expanding existing apps to incorporate iPhone OS 3.0-enabled capabilities, such as push notifications and MMS support (in some markets). They're evolutionary changes, much as the newest iPhone itself is evolutionary, but still offer an interesting look at where the iPhone hardware/software combo is headed.Here's a quick look at five applications iPhone and iPod Touch owners should consider. The easiest way to track them down is by accessing the App Store on the iPhone and searching for the app title. (You can do it in iTunes, too, if you want.)