Most online mapping products today feature transit directions. Sadly, though, it’s the nature of public transit that things often don’t quite run on schedule. Thankfully, quite a few transit districts have now track their buses and trains with a GPS system so that the public can know exactly when the next bus or train will arrive. For the most part, however, you won’t know this information until you arrive at the station (which is always either far too early or just too late). Starting today, however, there’s a better way to get this information quickly: Google Maps will now feature live transit updates in four U.S. cities (Portland, OR, Boston, San Diego and San Francisco) and two European ones (Madrid and Turin).

Google maps will feature both live departure times and service notices to Maps on the desktop, mobile browser and on Google Maps for mobile (Android 1.6+).

To give this a try on the desktop, just look for a transit icon on the map and click on it. If you’re in a supported city, you will see when the next train or bus will arrive and if there are any alerts that affect traffic to or from this station.