Our sister site iPhone Atlas has posted some screenshots of Apple's newly minted iPhone Software Development Kit (SDK), which is now available. The shots show a template chooser, an application organizer and the iPhone Simulator (dubbed "Aspen Simulator"). All program assembly takes place in Xcode 3.1, a new version of the integrated development environment for Mac OS X. Accompanying the development kit is a swath of documentation from Apple, including code samples, a series of instructional videos on iTunes and more. While the SDK is free, joining the iPhone developer program--which will provide technical support, code testing and allow distribution through the "App Store"--costs $100.