In yet another bit of awesomeness from the good people in Mountain View, Google has added arterial roads to it's real time traffic conditions in Google Maps. This added functionality will now display both main highways as well as alternative routes in it's results. While this will undoubtedly benefit users that have the app already installed on their mobile phones, it can also help those going to or leaving work make a more informed choice about which route to take instead of just taking that "secret" shortcut only to find that everyone else did too.
Mobile users will also have the option of sharing their data with Google to help update it's real time conditions. Users with GPS features on their smartphones can share location and speed to help update the app for the benefit of everyone.
Google plans to expand this functionality to all U.S. highways and arterial roads as information becomes available from users.
You can download Google Maps for mobile here. (It's free!) [shiny edit: I have this on my BlackJack and just want to mention that this is AWESOME. The BlackJack is overall average, but Google Maps makes anything awesome.]
Read more about this at The Official Google Blog and Google LatLong , a blog from the Google Earth and Maps team.