NVIDIA has announced that it will be dropping support for a large number of legacy cards to coincide with the release of its new driver. NVIDIA cards older than the GTX 400 will no longer receive full driver support (enhancements and improvements) after Release 340. While this might seem outrageous, some of these cards have been in circulation for several years.
While NVIDIA is discontinuing support for these graphics cards, it will not completely abandon them. NVIDIA will continue to provide limited support for driver issues and bug fixes until April 1, 2016. That means NVIDIA will have provided a full decade of support for some of these legacy cards, which seems more than reasonable. Those with cards not listed can expect to receive regular updates from NVIDIA. The latest release for newer cards will receive updates and enhancements through Release 343 and onwards.
NVIDIA also had a hell of a time shipping a driver that worked correctly with series 400 and 500 cards for almost two years, only fixing the freezing issues with release 323 onward. It's unclear if the decision to drop legacy support had anything to do with those issues.