The iphone will have the ability to support different types of multithreaded APIs, including: POSIX threads, Nsobject,nsthread, and Nsoperation.
iphone OS is a truly preemptive, multitasking operating system that allows developers to create multi-threaded applications.
With multi-threading, computer programmers can get their software to do multiple tasks at the same time. Sometimes it can take a few seconds for the app to complete a task, and in the meantime, you don't want the user to wait. For example, an app might need to download information from the Internet, and you might want to be able to see the activity indicator on the screen while the download work is done in the background, or navigate to other parts of your app. This responsiveness can be increased by multithreading for your application.
"Multitasking" improves performance with multithreading