This is pretty slick — Google Maps will now give you multiple estimated times for trips that you plan (in “a limited set of metropolitan areas”).
Their example has someone traveling from Berkeley to Half Moon Bay, which is “about 59 minutes”. However, the directions also say that it could take “up to 1 hour 50 minutes in traffic”. This allows you to look at multiple routes to determine which would be best if you had to travel during rush hour.
Obviously, this can’t account for accidents that might slow things down further, but it’s a neat addition. Combine this with the new click-and-drag directions, and you can quickly find the best route during heavy traffic times.
The Google LatLong blog has a full write-up with some nice screenshots.