Apple on Monday jumpstarted its next generation smart phone platform by releasing its new mobile OS, iOS 4, for current versions of the iPhone and iPod touch. On Thursday, Apple takes the next step by releasing the eagerly awaited iPhone 4 smartphone, which will include iOS 4 out of the box, as well as a number of unique hardware features.

Apple iOS 4 works a bit differently on different era devices. Users with the iPhone 3GS or third generation (late 2009) iPod touch will receive all of the features of the new OS, including multitasking. But users with the 2008-era iPhone 3G or second generation iPod touch receive only a subset of the iOS features. They will not receive multitasking capabilities, for example. Users with first generation iPhones or iPod touches will not be able to install iOS 4.

Aside from multitasking, iOS 4 provides a number of useful new features, including folder management of home screen icons, home screen wallpaper, a digital zoom control for the iPhone camera, and numerous improvements to all of the built-in applications. Apple is also delivering some new enterprise features in this release, including support for multiple Exchange accounts.

Apple will separately update its iPad tablet device to iOS 4 in September. It's unclear why this product is on a different delivery schedule, or what impact this will have on developers who wish to target both the iPhone and iPad with so-called Universal apps.

You can find out more about this update in my iOS 4 overview on the SuperSite for Windows.