here you will find public transit service advisory feeds in a variety of formats (XML, RSS) for systems all over the US (and potentially other countries).
first, we'll start with the New York City MTA subway system. future expansion is planned for:
also in the pipeline is an OS X Dashboard Widget, along with the design of this site once another one or two more transit system advisory parsers are in place.
stay tuned this summer for these and other new additions!