Current location button.

Pushing this button will show your current location. It will continue to update as you move. This is a nice feature, but you can get more info.

When you press the button again, the button will change.

Compass link button.

The maps app is now linked to compass and your location display will change to look like this.

As you move, more information updates the display by narrowing the white arc. The narrower it gets, the more accurate the direction.

This feature makes your iPhone work like a GPS unit allowing you to see turns ahead.