Layers make it easy to view various types of information on your map and are especially helpful in situations when you’re traveling somewhere new. For example, you can turn on the Wikipedia layer to read entries about nearby places, then use the transit lines layer to help map out a route. Or you can use the My Maps feature of Google Maps to create a collection of places you’re planning to visit on your trip and then use Google Maps for mobile to access it from the road. You can also turn on the Google Latitude layer to see your friends’ locations.
Excerpt from Google Mobile Blog.I’ve been using Google Maps for several day to replace BlackBerry Maps. One thing I like about Google Maps is its search function that actually work. Now comes the Layers. I still don’t see any requirement to this feature comes out from my routines. But only time can tell.