Microsoft already uses NAVTEQ maps in its products, and now it's going to start helping to make 'em better: the two companies have agreed to work together on new ways to collect, create, and store 3D map data and visuals. The basic idea seems to be for Microsoft to help NAVTEQ create better 3D mapping tools in return for supplying the data for Bing Maps, but NAVTEQ says whatever improvements are made will be rolled out to all its clients, so this should pretty much benefit everyone.
P.S.- This is a pretty wonky note, but remember that NAVTEQ is wholly owned by Nokia
(although it operates independently) so this is technically the second Microsoft / Nokia alliance
announced in the past four months. Ah, young love.