One of the major shortcomings of the iPhone is that, for all its many apps, you can only run one at a time. Want to check your email while you read the NY Times? You'll have to close the NY Times app and open the email app. It's annoying!
New rumors predict a new overhaul of the iPhone software this summer, coinciding with the release of an updated, more powerful iPhone. The software would allow a robust form of multitasking, allowing you to run multiple apps at once. Finally! Now we'll just have to wait and see if the rumors are true.