These things have been in development for some time, and I still wonder how effective these would be in more realistic situations, but it does appear that real progress has been made.
How useful would it be for ships? That depends on many things, including how military aircraft might be able to follow a jerky, unpredictable path that might impede the ability of the laser to stay on one spot long enough to start a fire or cause damage.
On the other hand, something like this might come in very handy on towers around cities like Washington, D.C., or New York City. Remember how the Secret Service had no way to prevent a small plane from crashing into the White House? This kind of technology could take care of that problem. It could also be effective against September-11 type attacks using commercial aircraft, which cannot dodge and juke like military aircraft. Mounted high on broadcast towers, the lasers would be much less obvious than orbiting military planes, would have easy access to the power grid, and would have a clear view of the city sky.
I have no way of knowing whether or not these things have been installed to provide anti-aircraft protection for cities. Then again, it's not the the kind of thing that would be announced, since if the locations of the lasers were known, their access to power could be shut down.