The iPhone, iPod Touch and iPad all use the same operating system although the iPad when launched will run version 3.2. There are a few differences in OS 3.2 which can now be put on to the Apple [AAPL] iPhone.
To achieve getting the 3.2 functionality on to OS 3.0 on the current iPhone you need to jailbreak your phone first. Once done you can simply install a number of apps that replicate the functions of the iPad such as a new iBooks Store, iWorks suite etc...
Full details of how to do this are included in the video below which goes through a step by step guide on converting your iPhone over.
A list of the apps can be found just below which you will need to install to get things working...
* Winterboard app via Cydia
* 'Simple iPad Theme via Cydia
* MakeItMine app via Cydia to Change the Carrier logo to iPad.
* Shrink app via Cydia to reduce the size of all the icons on the springboard.
* ProSwitcher via Cydia for Multitasking.
* NYTimes The New York Times app for iPhone via App Store
* Classics The iBooks lookalike app for iPhone via App Store
* Kindle for iPhone via App Store
Via: Redmondpie