According to Computerworld, IBM has developed a novel technology to allow sharing of data on common individuals without compromising the privacy of those who are not known to the two parties. I may not fully understand the math behind it, but it appears that the technology allows two separate organizations to encrypt databases for sharing with the other. Information that is common to both will be the same when double-encrypted, but information encrypted by one of them will not be readable by the other. So if Person A is known by both Company I and Company II, they can each decrypt and read the info about Person A. But if only one knows Person B, the company that does not know him/her cannot read that data. This is not the holy grail of privacy, but the article outlines some interesting applications: IBM Almaden Research Center's Sovereign Information Integration Privacy-Minded Security - Computerworld.