As noted in our review of the Lumia 800, the Nokia Maps app was curiously missing. It's now available from the Windows Phone Marketplace, if you happen to have a Nokia Windows Phone.
Nokia and Microsoft have said that Nokia Maps won't be exclusive to Nokia phones in the future, but it looks like the beta is locked down to Nokia's own handsets for the time being. It's not listed in searches, but can be download directly from the application page or through the place-holder app on the Lumia phones. Of course you might be able to grab Nokia Maps on a non-Nokia phone with the help of ChevronWP7 Labs, if you truly hate Bing Maps. [All About Windows Phone]