On Tuesday a cyclist told me that the 9:15 train coming in to MP southbound was going to have only one bike car! She said twitter told her.
It's easy to sign up for the twitter feeds.
1) Create an account at twitter.com and set it up the way you want it.
2) Follow "bikecar" (http://twitter.com/bikecar) for bike car info. (There is also a "caltrain" (http://twitter.com/caltrain) for general
Information on how the accounts work and how to get set up to post to the bikecar or caltrain accounts is at http://cow.org/c/.
It's realtime information about Caltrain service provided by fellow riders.
Thanks to Alexis.