The MTA is obviously taking the hint that it hasn't done nearly enough to protect the city's vulnerable subway system, especially in light of the terrorist bombings in London.
The MTA apparently has had access to a massive war chest of hundreds of millions of dollars in federal funds, but has spent only a fraction of it. Now there's talk of installing hundreds of subway surveillance cams throughout the subway system, similar to what London already has. This is an election year, so "it's a safe bet that at least some of the cameras will be up before Bloomberg faces re-election in the fall, and certainly by year's end."