One of the newly improved features of Live Maps is the traffic re-routing feature, called Clearflow, which can re-route Live Maps directions based on traffic information.  The new system, updated initially for 72 US cities, takes into account not only major traffic routes but adjacent city streets as well.  I tried out the directions, with Traffic switched on:

Hmmm green lights all the way on this route, smooth sailing.  Anyway, if you run into traffic, you just click on "choose route based on traffic"

Actually I've tried the traffic routing in other locations, it's pretty cool.  Of course if you're a Seattle to Redmond Microsoft commuter, there are only 2 bridges across the lake, doesn't take advanced algorithms to figure out which one is best :).

If you're looking for the easiest way to get from say Mountain View to Sunnyvale, give Live Maps a try!