The feed itself is here:
http://www.caltrain.com/google_transit_feed/
With some license text here:
http://www.smctd.com/dla.html
The GTFS format specification is here:
http://code.google.com/transit/spec/transit_feed_specification.html
And there's a list of other public feeds, along with Python and Java
code for feed processing, in the GoogleTransitDataFeed project:
http://code.google.com/p/googletransitdatafeed/
Thanks to Elliott Schwartz for requesting a feed from them while back,
and to everyone at TransitCampBayArea!
Joe