Since their merger with GDT, TeleAtlas has been in process of combining two massive databases and data collection processes. On the former GDT side, they use aerial imagery with hand-drawn roads augmented by schematics from governments and other sources. On the former TeleAtlas North America side, they have fleets of vehicles driving the roads. While this database merge project is a monumental undertaking, it offers the possibility of geographic data set with greater currency than either process by itself would allow.
NAVTEQ traditionally has gathered the vast majority of their road geography through fleets of drivers. It will be very interesting to compare the quality of the NT versus TA data going forward.
Good though brief summary of the project in a DirectionsMag article by Marilyn Otto of MapInfo.