A couple of years ago, Google launched the Google Transit service which allowed users to plan trips on an interface very much like Google Maps, using schedule data from transit agencies in various cities. (In fact, Portland was the first city chosen for this service.)
Recently, Google began integrating features of Google Transit into the main Google Maps interface… most noticeably in the form of icons representing transit stops on all map results (in supported cities). The icons are clickable to view transit lines and arrival times. There is even a special icon for the Aerial Tram.
Earlier today, the site WorldChanging.com published an article detailing the improvements to Google Transit… it covers a lot of ground and is worth a read.