Multitasking, the feature that has been the absolute top of every iPhone user’s want list –which, by proxy became a major marketing point for both Android and webOS — has made its way to iPhone OS 4.

“We figured out how to implement multitasking for third party apps and avoid those things [battery life and lag]. So that’s what took so long,” said Apple CEO Steve Jobs this morning.

While it’s not actually full background processing, Apple has devised a way to reproduce the feeling. The company provided 7 APIs to developers which constitute the always-on services that apps can communicate with. These include: background audio, VoIP, Background Location, push notifications, local notifications, task completion, and fast app switching.

With these 7 services in place, users can now run music apps like Pandora in the background, they can run location-aware apps in the background, or can run VoIP apps. With a double-click of the home button, the user can pull out of the app he’s currently in and go to a list of running tasks. If you back out of a game to check your email or answer a Skype call, the game can then pick up and resume where you left off.

We’ll follow up with more on the iPhone OS 4 update as it arrives.