Not sure where this should go, so why not in SE. Here is an academic paper on the topic by researches from Carnegie Mellon University that was just released on the Proceedings of the National Academy of Sciences web site and a couple links to articles reporting on it.

Predicting Social Security Numbers from Public Data

Report: Social Security numbers can be predicted
CNET - http://news.cnet.com/8301-1009_3-10280614-83.html
CNN - http://www.cnn.com/2009/TECH/07/07/social.security.numbers/index.html

Let the discussion begin...

Don

I have two brothers (two years apart, so this spans four years) and we all have the same first five numbers.

I was in the service some years ago and I remember personnel specialists being able to tell you your place of birth based on your SSN.  It was a big joke.  Some of them claimed to by psychic.  You'd put your home of record as being say Utah and they'd say, "but you were born around San Francisco, right?"  Everybody would chuckle and life would go on.

My wife does medical work and turned me on to the Social Security Death Index.  This is a database where you can find out if a particular social belongs to a dead person.  I started thinking years ago that with that data (to help bracket in the last four numbers based on birthdate) and the first five that were already easily guessable that you'd be on a legit number in no time.  Bad news is that the SSDI is freely available via many genealogy sites.