You can indicate via the Info.plist that your application doesn't support multitasking. The app will run through the full startup and shutdown routines on foregrounding and backgrounding.

I am thinking more system wide. It was not uncommon for people to hit the home button as a sort of "escape".

In what scenarios can they not do that in the post-iOS 4 world?

there are plenty of apps that don't go back to their start point on hitting the home button and re-entering the app.

Ah, I read what you wrote to mean that users could no longer "escape" using the Home button. Thanks.