The Windows Phone 7 navigation application, Outdoor Navigation has been recently updated to bring offline maps into play. Version 1.3 will allow you to download maps to your Windows Phone so you can use map features when you travel outside your coverage area and lose data connectivity. This feature also comes in handy if your service imposes roaming charges on data.
We felt that this was one feature missing on Outdoor Navigation (here's our review) and offline maps will only add to a very good navigation app.
Version 1.3 also has added German and Italian as language options. It is our understanding that additional languages are in the works. Lastly, Version 1.3 adds two map styles to Outdoor Navigation. OpenPisteMap with ski slopes and OpenHikingMap with trails has been added.
There is a free trial version for Outdoor Navigation with the full version running $4.99. You can download either here (opens Zune) over at the Marketplace.