I had forgotten how current the Social Security Death Index is at GenealogyBank.com. My wife’s brother passed away on 10 Oct 2010 and his entry is already in the index. Others are not updated quite so quickly. So if there’s a death you know happened fairly recently, you might want to check Genealogybank’s version of the SSDI. Others are not updated quite as quickly.
The reason the Index is updated so quickly is that banks and other institutions use it as a means to catch people using Social Security numbers of recently deceased people.