And about MGMaps: its services are based on Yahoo! Maps, Windows Live Local (MSN Virtual Earth), Ask.com, Open Street Maps. So you have to agree each Terms of Service if you use one or another maps.
I understand that all these restrictions doesn't come from Yahoo or Google themselves, but from maps providers (Navteq, teleatlas, and so on), so they keep the rights to commercialize map navigators and tracking software for vehicles.
The only free implementation there is OpenStreetMaps, that's already being discussed in another thread here in AndDev.
Aside this free implementation, the Terms of Service that seems is free to use with navigation and driving directions is Microsoft's MapPoint Web Service: http://www.microsoft.com/mappoint/webservice/terms.mspx
The only drawback here is that the map providers are the same than Google's and Yahoos', and maybe it's a matter of time that they add some restriction clause to the ToS. But for now, it's usable.