Web-like tabs for the iPhone

My approach to a similar problem was to make all 4 (in my case) tab views, but respond to didReceiveMemoryWarning by releasing all but the current tab view. (Then, of course, you must make sure that you create the new view, if it doesn't exist, when the user chooses a new tab.)

I thought this was a good compromise - a speedy reaction to the user at first (and in my case memory footprint is at its lowest at this point in my app), and then a response to low memory to avoid being shot.