From the Google Blog:
"With it, commuters will be able to easily access public transit schedules, routes, and plan trips using their local public transportation options. This first release covers only the Portland, Oregon metro area, but we are working to expand our coverage very soon."
The few engineers that started the project all regularly use public transportation, says the Google post.
Here's an example of a trip from 4412 se 17th ave portland, oregon to hillsboro, oregon.
"20 percent time," according to Google:
"Google engineers all have '20 percent time' in which they're free to pursue projects they're passionate about. This freedom has already produced Google News, Google Suggest, AdSense for Content, and Orkut -- products which might otherwise have taken an entire start-up to launch."