AppleInsider claims to have exclusive details on how multitasking will work in the next major iPhone OS. Predictably, it's a lot like Expose works in OS X.
...reportedly hitting the Home button twice will trigger an expose-like interface that brings up a series of icons representing the currently running apps, allowing users to quickly select the one they want to switch to directly. When a selection is made, the iPhone OS zooms out of the Expose task manager and transitions to that app...[but]scaling down several screen views to fit into the relatively small display would be problematic, and apps never have multiple windows, so the new mechanism currently presents just each app's icon.
Apparently the experience is a hybrid between Expose and the Command+Tab app switcher - meaning it may look less like Expose than HTC's Android-based Helicopter View.
Other upgrades include adding individual contacts directly to the iPhone's home screen and a "global mailbox view" that probably handles multiple accounts with more finesse. [AppleInsider]