In Ice Cream Sandwich Google introduced new icons to unclutter and streamline the interface. Only problem is that people don’t know what they mean and that means it would be counterproductive. Well they’ve given some advice:

In Android 4.0 Ice Cream Sandwich, we’ve added several new icons to make using your Android device faster and easier. If you ever wonder what an icon means, you can long-press the icon and the name of it will appear. For instance, when viewing a message in the Gmail app, long-press on the sealed envelope. The icon will appear against a blue background and the description ‘Mark unread’ will show on the screen. You can use this trick in other Google apps, such as Calendar, Talk, and Maps in Android 4.0.

That helps.