There are so many cool applications being built that take advantage of Google Maps technology.
Over the weekend I tried out Google's new Local For Mobile on my Motorola V400 cell phone and it worked nicely! I used it to search for all the shoe repair places near where I live. This is probably the first useful J2ME application I've used on my cell phone. I had to enter my zip code in order for the application to know where I was, but I heard that on some phones, cell tower triangulation can be used to automatically identify your location. Unfortunately GPS isn't used yet but hopefully will be in the future.
Another application that is gaining popularity is Frappr. People are using Frappr to create group web pages that show where members of the group are physically located. For example, one of the podcasts I listen to uses Frappr to guage where its listeners are located: Slashdot Review Podcast Frapper Page.
One last example of a cool Google maps-enabled application is MashMap. This one makes it really easy to find what movies are playing in nearby movie theaters. The user interface is pretty slick.