The Problem with the iPhone's Home Button
I have a similar problem on my Droid X.  Sometimes the back button goes back a page (such as in a web browser) or while reading a message back will go to my contacts list (in google talk or google voice).<p>But sometimes, in the same apps, the back button might take me back to the home screen (If i answered a message from the notification bar), or a previous app if something launched a browser.<p>It's incredibly aggravating that the behavior changes, and especially so as Android devices have a home button!  Back should be constrained to a specific application.  Otherwise in google talk I have no reliable way to get back to my contacts and usually have to make a trip back to the home screen to directly launch the talk app.