I blogged about the digital display testing on the 2-3-4-5 platforms awhile back, and it seems the MTA is going ahead with plans to implement the use of the displays for train arrival information in all numbered-line (IRT) stations by the end of the year. In order to cut costs and make the system work for lettered-line trains, however, the MTA is trying to use existing technology instead of installing the new gear you see on the L (and now on the 6 line in Bronx). The only drawback? The system doesn't know which trains are coming, just that something is moving down the line. As long as they can differentiate between express and local trains (and the signs in the press release suggest that they can), I think that's fine. If not, well, the only thing more annoying that standing for 20 minutes at the Franklin C stop as three A trains go whizzing by would be listening to an announcer's voice tell you that your train was about to arrive over and over.