Jason,
Good news, we are planning on releasing this information later this
year! First, we will be releasing a pilot feed of commuter rail
location information later this month. This set of data will include
train locations and predictions for Commuter Rail. Predictive
information will only be available once a train is on the move. Until
that time, scheduled information will be shown (much like bus).
The data set we include information from departure boards at North,
South, and Back Bay stations. Later this year, we expect to make that
data available to developers and customers.
Josh