An analysis of state-wide records by the Poughkeepsie Journal reveals that 77,000 dead people remain on election rolls in New York State, and some 2,600 may have managed to vote after they had died. The study also found that Democrats are more successful at voting after death than Republicans, by a margin of four-to-one, largely because so many dead people seem to vote in Democrat-dominated New York City. (Link via Ed Still's VoteLaw.)
UPDATE: Contrary to the suggestion of some commentators, I made no claim of fraud. It's obvious that dead people are not actually voting (at least, obvious to those of us who reject claims of the paranormal). So, to repeat a finding that dead people are voting simply means that either a) live people are casting fraudulent votes in the name of dead people, or b) live people casting their own votes are wrongly listed as being dead. As some commentators noted, the story swuggests the latter is as, if not much more, likely than the former. Either way, official records show people voted who are supposed to be dead. In any event, I wrote that "some 2,600 dead people may" have voted, but I probably should have said "up to" or "as many as" to be more precise.
For much more on this than you may want to read, see Mark Kleiman's post here.