Multitasking capability has arrived with iOS 4. Users with an iPhone 3GS or iPhone 4 who have the latest firmware installed can access the feature.
Any apps can run in the background. For multitasking features such as background music to work, the application running in the background must be updated to take advantage of the capabilities Apple has added to iOS 4.
To use multitasking:
1. Run an app.
2. Press the home button. Instead of quitting the app will run in the background (apps without background support will quit).
3. At any time, double press the home button.