What are the implications of multi-tasking in iOS 4.0 for developers?

I just watched this video from Apple that shows multi-tasking on the new iPhone (running iOS 4.0). What are the implications of multi-tasking to developers? Include both positives and negatives.

For example what happens if the user decides to launch two resource-intensives apps at the same time, one of the apps crashes and progress in a game (for example) is lost. Should developers be considering th开发者_JS百科is when writing apps for the new OS and phone?

For example what happens if the user decides to launch two resource-intensives apps at the same time, one of the apps crashes and progress in a game (for example) is lost?

One of them will run on foreground. If the system gets thin on resources, it will terminate the one running in background. The application always gets a chance to save its state.