Apparently the Social Security Administration put a new law in place in July 2011 to provide a level of protection against identity theft. See https://secure.ssa.gov/poms.nsf/lnx/0203350005 , paragraph I. Under this new law, a complete copy of an SS-5 form will only be provided if the deceased person was born more than 100 years ago and you can provide proof of death or was born more than 120 years ago if you cannot provide proof of death. The goal here is to protect the privacy of the deceased's parents. The SSA appears to have put this law into place without even allowing for a public comment period.
I didn't know this 3 months ago when I requested a copy of the SS-5 for a grand-aunt who passed away earlier this year. I was just curious about where she was born. They did send me a copy of her SS-5 but her place of birth and parents' names were blocked out. The copy was accompanied by a letter telling me that it is not in the public interest to release this information but that they would release it if I could provide proof that her parents are deceased. I submitted an appeal 2 weeks ago but I assume now that it will be denied because my aunt was born in 1918. In my appeal I stated that I couldn't provide proof of death for her parents because I didn't know their names and, also, they would both be 110+ years old if they were still alive (not a reality for many people, especially not Eastern European immigrants born before 1900). The SSA did keep my $27 of course.
I just sent an e-mail to Ancestry.com asking that they place a clear warning in their SSDI FAQ so other researcher don't throw their money away. The information that is being blocked out on the SS-5 form is the only information on the form worth $27.
Update: the SSA denied my appeal, 1/19/2012