iOS4 multi tasking and battery life

This post might be techie for some, however I will try and keep it as simple as possible.

Multi tasking provides a user with the ability to run applications in the background. For example, you can have iPod playing music on the iPhone 3G while you surf the internet. This exact form of multitasking permitted by Apple has always existed. However, you were unable to open 3rd party applications such as Pandora (music streaming app) and surf the internet at the same time.

With iOS4, 3rd party applications can now open in the background. However, only for applications using the phone's multi tasking services for audio, location and voice over ip (eg. Skype). Technically there's task completion too as a service.

Some say this is not full multi tasking.

However, Apple is quite clear about why they have designed multi tasking in this way. To preserve battery life and maximise performance. Gizmodo has an article on this.  This appears to be a very reasonable design goal.

Android allows for "full" multitasking, however it drains battery life.  Google has acknowledged it.