The Mystery Behind iPhone's "OS X"

Apple's iPhone runs OS X. It was announced at the keynote, but not a whole lot of information has actually been released on the finer points of the no doubt modified version of OS X running on the new phone. John Gruber goes into excellent detail regarding the misconceptions formed by referring to the UI present on the iPhone as "OS X."

Macworld's own report of the iPhone reveals the actual space taken up is a mere 500 MB. Clearly a full-fledged version of OS X isn't present, as most OS X installation system folders are in excess of 2 GB.

OS X has many features that aren't necessary for a mobile phone, from hardware drivers not necessary for the iPhone to all applications developed for the Mac UI. In contrast there are several features required for a cellphone that OS X does not offer, as well as the new multi-touch screen support.

In actuality the iPhone may not run a bit-for-bit translation of OS X, but at it's heart you can be assured you're getting something very similar in nature.