Apple’s upcoming iPhone OS 4.0 will allow users to run multiple third-party applications at once, managing these through an interface similar to that of Mac OS X’s Exposé feature, according to an AppleInsider report. Citing people familiar with Apple’s plans for the new software, the report states that users will employ a key combination—possibly a double-tap on the Home button, which currently triggers a user-definable action—to trigger an Exposé-like interface that will present a series of icons representing currently running apps, letting users switch in between them. Once a selection is made, the interface reportedly zooms out and transitions to the selected application. Additionally, the report claims that the new software sports a global mailbox view and the ability to add contacts directly to the home screen, although it notes that either one, or both, of these features could be cut before the software is released. Daring Fireball’s John Gruber mentioned iPhone OS 4.0’s third-party multitasking capabilities in a brief posting earlier this week, while Apple CEO Steve Jobs recently confirmed in an email to a customer that a universal mailbox would be coming to the iPhone.