YAY! Multitasking is coming to your iPhone, iPod touch and iPad. Apple claims their method will save battery life and resources, unlike the competition. This is how they are going to do it. [Updated live]

How Does it Work for Users?

Here's one example: If you are working on email and there's a link to a web page, clicking on that link will open Safari. In previous versions, that will close Mail and launch Safari. Once you were done watching that web page, you would close Safari, get back to the main iPhone menu, click on the Mail, and go back to your mail.

In this new version, Mail keeps running—in a dormant state—and Safari opens. To go back to Mail, you just double-click the home button: A dock will slide in from the bottom of the page, showing the running apps. Click on any app to switch to the app.

How Does It Work for Developers?

First of all, this is not 100% true multitasking. That will consume too many resources, specially memory—which will make the system choek—and CPU—which will also deplete battery life quickly.