Multitasking & Fast App Switching in iOS 4

The most interesting part of this article, to me, is the UI issue raised at the bottom (although I feel it'd be more correctly classified as a user experience issue).

In the current version of iOS, I often find myself hesitating after kicking off a non-instantaneous action, like hitting "Send" in the Mail or Messages apps.

Since these actions complete an interaction, I have a strong instinct to immediately click the Home button and move on to whatever it is I'd like to do next.

But, since "switching" is the same as "quitting", I hesitate: if I switch before the mail is sent, will the app finish doing what I asked it to do first? In the case of those two apps, the answer is yes, they will, but I have no way of being certain. The safest thing to do is wait until I know the action is complete.

Since iOS 4 makes it much easier to complete tasks and save state, there's a good chance my mental model will shift from switching == quitting to switching == switching.

At that point, woe unto any app that breaks that model and actually quits, either losing some state or not performing some task I cared about.