Google Maps back on iPhone after Apple software fiasco: http://www.bbc.co.uk/news/technology-20694028
MapsGL (maybe after Bing maps 3d imaging?)
Google has stated they have no interest in developing apps for the Windows Phone platform. However, there is a third-party app called gMaps. This app seems to be the most widely used Google Map app for Windows Phone with over ten thousand reviews and a near perfect rating.