Hi Kim.

I looked at the Tiger2000 documentation as well. I stumbled about this (at page 5-6 and following):

Coordinates in the TIGER/Line® files are in decimal degrees and have six implied decimal places. The positional accuracy of these coordinates is not as great as the six decimal places suggest. The positional accuracy varies with the source materials used, but at best meets the established National Map Accuracy standards (approximately + ⁄– 167 feet) where 1:100,000- scale maps from the USGS are the source. The U.S. Census Bureau cannot specify the accuracy of feature updates added by its field staff or of features derived from the GBF/DIME-Files or other map or digital sources.

Thus, the level of positional accuracy in the TIGER/Line® files is not suitable for high-precision measurement applications such as engineering problems, property transfers, or other uses that might require highly accurate measurements of the earth’s surface.

Despite the fact that TIGER/Line® data positional accuracy is not as high as the coordinate values imply, the six-decimal place precision is useful when producing maps. This precision allows you to place features that are next to each other on the ground in the correct position, relative to each other, on the map without overlap.

Now I'm wondering: A +/- 167feet accuracy (about 51 meters) isn't even as good as GPS is. And around my house, 167feet is surely more than the space between two parallel streets.
I guess this could be corrected with the aid of the user (like the CityMaps and RoutePlanner apps from www.palmtop.nl are doing it), but how often would that be needed on long distance drives?
I am still trying to find out how much efford (money and contract wise) it would be to license the TeleAtlas data format. Those maps are far more accurate (within the 10meter range) and available for almost any country in the world (with differing detail levels though).
Anyway, let me drop a word on why I even investigate nav software development while you obviously have a pretty mature application done: You only released some teasers, but almost no specific until recently, and I didn't see that changing. Now that you seem to be willing to release your application (be it open source or not), I am doing all I can to assist you.
If I could collect some GPS positions of street interconnections, along with information about those streets (like direction, speed limit, name), would that be enough information for you to create a suitable map? If so, I would be willing to collect that information for the area of the next owners meet (about a square kilometere or two), so that your application could be demonstrated there.

cu,
sven