Google announced on Google+ that the new Android Google app update will automatically add to Google Now traffic notifications without you asking for them.
For me, I always check Google Now and Apple Siri before I head to work or leave work. It always (unless it is confused - Glass hasn't been showing me this since I came back from SMX West) shows me the traffic and time to work or home before I leave. It has saved me tremendously with avoiding traffic.
But now, you don't even need to look for it. Google Now will tell you if it thinks you are on your way and you are about to get into a traffic situation that you'd prefer to avoid.
Starting today, you’ll have a better chance of making it around the traffic. With the latest update to the Google Search app for Android, Google Now will send you a notification if you’re likely to hit a traffic incident along your drive—without you even having to ask. That way, you can get off at that earlier exit and cruise through the back roads.
Google Maps traffic is awesome, Google Now is awesome - blending the two is even more awesome.
Forum discussion at Google+.