Interesting.

I just used the 2000 TIGER data and 2000 population counts. So certainly if you can send me an update I can repost.

I work mainly with socio-economic data, so I don't keep up very much with the transportation world.

Also, I should have noted that even though the boundaries are more accurate than that displayed with the Census Bureau's generalized boundaries, there still are discrepancies with the overlay. It seems impossible to perfectly match the Census Bureau geography to Google Earth and Google maps street lines.