iOS4 — the Return of the Desktop Paradigm (partially)
On the iPhone platform this concept was extended beyond file types to tasks. Instead of files and folders we got apps. While technically apps (programs) are still files, it doesn't seem like that to the user. Apps are perceived as small function clusters, not "files". Like precision tools they offer their services to complete a huge variety of tasks.
The overwhelming success of apps seems to have made it necessary to introduce folders in the new iOS4. In order to organize and make room for more, apps can now be collected inside folders.
A folder is created by dragging apps on top of each other, which creates a custom icon. If you tap on it, the home screen is being sliced open as if cut by a surgical instrument to reveal a sort of drawer underneath, — containing a cluster of apps. Meanwhile the rest of the screen becomes desaturated and semi transparent to create more focus. All of this is done beautifully and clearly. Apple really masters the soft part in "soft-ware".
And yet, once you start to put apps in folders, the desktop paradigm (thinking files in folders) creeps back. Until iOS4, one of the most arresting things about information display was the absence of hierarchy on the home screen and in apps like iPhoto. Like cards on a table, apps and images were displayed on the same "swipeable" 2D plane. Edward Tufte explains that beautifully in his video on "Information Resolution".
Email in iOS4
To be fair, adding a combined email box for all email addresses just decreased the level of complexity by eliminating tons of back and forth clicks and is a good thing..