Via the Google Operating System blog
Google Maps shows real-time information about traffic for many US cities (like Kansas City, New York). To see this, switch to the map or hybrid mode and click on the new traffic tab. Google Maps will add a layer that colors the roads in green, yellow, red, or gray. The colors represent how fast the traffic is moving:
* Green: more than 50 miles per hour
* Yellow: 25 – 50 miles per hour
* Red: less than 25 miles per hour
* Gray: no data available
Until now, this feature was available only in the mobile client of Google Maps.
Update: the official Google Blog mentions that it’s available for 30 major U.S. cities. No word on who’s providing the data.
What it means: this is cool. Google just added the fourth dimension to local search: time. Another “time” application would be to show businesses that are currently open, depending on the day of the week or the time of the day.
Seb Provencher's Blog 
Great point. I agree time could be an incredibly important dimension in search generally, and local search specifically. Along the nav/GPS lines, how bout they also show me what businesses will be open when I’m due to arrive if I give them a trip start time. I can then check off the ones I’m interested in, and my GPS (mashed up with Google and my cell phone of course) alerts me when my predicted arrive time is after close for the checked businesses.
It’s cool, but of course both Yahoo and Microsoft with Live Search have had this feature for quite a while. Including versions for Java-enabled phones and Windows Mobile Smartphones.
http://maps.live.com
http://wls.live.com (from your phone)
Hi Mike,
Thanks for your comment. Good point! I actually had seen a demo at Microsoft Mix 06 last year during Microsoft Research’s presentation. So, I should have mentioned it. Bryan Mistele, CEO of Inrix, had demo’ed the technology.