The early-warning radar of the Voronezh-DM class that was built in the Kaliningrad region, was formally accepted for service today. The station is located near the old Dunayevka air base (it was first found at Yandex Maps, which was a bit better than Google in updating its imagery of the place).
Bringing the Kaliningrad radar to operation was included in the series of measures that the President of Russia announced last week as a response to the U.S. missile defense plans. The link between the Kaliningrad radar and missile defense is rather artificial - the radar is part of the early-warning system that in no way can counter U.S. missile defense deployment.
It is not clear if the radar is fully operational - according to earlier reports, some elements of the station were already operating in January 2011; the radar was not expected to reach full operational status until 2016. Since radars of this class have modular structure, it is possible that even though the Kaliningrad radar could begin combat service today it would not reach its full capability until several years later.
UPDATE 12/01/11: As expected, the radar has not yet achieved its full capacity. It appears that it can work at about 12% of its full potential. This roughly corresponds to the fraction of the antenna area that has been completed to this date (see the link in Alexander's comment below).