At least it does if you live in one of the six cities Google has so far partnered with. Boston, Portland, San Diego, and San Francisco, as well as Madrid and Turin across the pond, have all worked with Google to include a real-time schedule of their public transit systems in the latest version of Google Maps. This update brings peace of mind to commuters previously left waiting at stops, with just the knowledge of when their bus should have arrived.
This update comes to the official Google Maps Android app, as well as the desktop and mobile web-apps. While the service is initially only available in the 6 cities mentioned, Google says they're working with several other public transit authorities to expand the "live departure times" feature to other cities. In the meantime, the service is now live in those cities, so if you're a commuter in one of the six, try it out.
The feature is built right into maps and navigation. If you click on a supported transit station in maps, it will display the schedule, with special icons indicating "live departures." Navigation using public transit will also utilize these real-time schedules when available, helping you get a more accurate arrival time.