iPhone OS 4 Task Switcher and Spatiality
I have already said how I think the iPhone OS 4 task switcher unnecessarily duplicates the functionality of the home screen. Beyond being an addition that is not needed, I think that, if used, the task switcher is harmful to the home screen.
The home screen makes great use of your ability to remember things spatially. Lukas Mathis has written about this before.
Apps are supposed to exist on home screens, some in folders and some at the bottom of the screen in the dock. The tray appears at the bottom of the screen, where the dock is, and can hold apps from anywhere on the home screens. The tray can even slide between screens just like the home screens. Except the screen an app appears on in the tray has no relation to the the screen it is really on.
The OS 4 tray pollutes your mental modal of how your apps are arranged. This might not be a problem. We can already use Spotlight to go to apps. The thing is, Spotlights does not look like the home screens: it shows a list rather than 57 by 57 pixel icons so is clearly different.
My argument here is based purely on theory. The problem I have described might not be real. I would not know without using the software but I do know that I like the simplicity of switching between apps with the iPhone as it is now.