One of Yahoo’s most respected researchers, Raghu Ramakrishnan, who is the author of one of the most famous database textbooks, “Database Management Systems,” has left the Silicon Valley company to join Microsoft. He was also critical to the development of much of Yahoo’s personalization technology.

Sources said the chief scientist for search and cloud platforms at its Yahoo Labs unit will be a fellow on the software giant’s SQL team.

Ramakrishnan, who has been at Yahoo since 2006, is one of many key researchers to depart before what is expected to be a gutting of the company’s research division in upcoming layoffs and other cuts by new CEO Scott Thompson.

None of this exodus of high-level research talent comes as a surprise. Prabhakar Raghavan, the well-respected head of the Yahoo Labs unit and also recently its head of strategy, has recently left the company to take a job at Google.

Ramakrishnan came to Yahoo from a professorship at the University of Wisconsin-Madison. According to his bio from Yahoo, he was the “founder and CTO of QUIQ, a company that pioneered crowd-sourcing, specifically question-answering communities, powering Ask Jeeves’ AnswerPoint as well as customer-support for companies such as Compaq.”

A Yahoo spokesperson declined comment (but, trust me, it is true).

The move is especially interesting because Adams had prepared an influential slide deck about the shortcomings of today’s social networks that was widely circulated online as well as within Facebook. Originally presented at the Voices That Matter Web Design Conference in June, “The Real Life Social Network” has been viewed more than 400,000 times since being posted on SlideShare.

For Adams to join the opposition is obviously not a vote of confidence for Google and its much-maligned plans to offer more social products.

Adams, who had spent four years on the Google user experience team, didn’t specify what his new gig at Facebook will be. At Google he had worked on products such as Gmail, Latitude and YouTube, according to his bio. Adams is also the author of the forthcoming book “Social Circles.”

After seeing Adams’s tweet this afternoon, I took some time to replay his 224-slide presentation.

In the last five months, Facebook released a Groups feature that addresses some of the problems Adams identified in online social networking, but his ideas and principles have not gone stale. Adams’s main thesis is that online social networks have not evolved to accurately portray and extend the offline social networks people have had forever. He compares Facebook friend lists and IM chat contacts to the awkwardness of planning a wedding seating chart, where people from all parts of your life come together.

While tools like email exist to help people communicate with those they are most strongly tied to, and services like Facebook help us keep track of our “weak ties,” Adams speaks of a need for a third model of “temporary ties” that recede after a short-term period, like an eBay transaction. He also talks about the opportunity to capitalize on the high degree of influence that friends have on each other’s purchases.

Adams proposes that people will increasingly need to have more than one online profile, and that online social products must be designed with privacy and trust at top of mind. He says well-designed social products must communicate to users the consequences of their actions.

These are interesting principles, but they’re hardly a blueprint for Google’s long-awaited social offerings and upgrades. The big difference is that now Facebookers can go straight to the source rather than being a few of the 400,000 people to view Adams’s ideas and research online.

Please note: As disclosed in my ethics statement, my husband is a part-time researcher on the Facebook user experience team.

In 2000, his team dropped the hammer on the Hack SDMI challenge by demonstrating how easy it was to crack the decidedly mediocre Secure Digital Music Initiative.

Dragged into the Sony BMG CD copy-protection scandal in 2005, he discovered that Sony’s “fix” for the Digital Rights Management rootkit it used to protect some new music CDs furthered inflamed an already bad situation.

And then, of course, there were Felten’s various investigations into electronic voting machines, the most notorious being the one that revealed Diebold’s machines could be opened with a standard office furniture key. “The access panel door on a Diebold AccuVote-TS voting machine–the door that protects the memory card that stores the votes, and is the main barrier to the injection of a virus–can be opened with a standard key that is widely available on the Internet,” Felten wrote at the time. “The exact same key is used widely in office furniture, electronic equipment, jukeboxes, and hotel minibars.”

Thank God for Felten, right?

And thank God the FTC has seen fit to hire him. There’s a lot of good he can do there. As Felten described it, “My main job will be to advise the FTC leadership on technology policy issues. My goals are use my technical expertise and knowledge of the tech world to help the FTC make the best decisions on tech topics, and to contribute to building up the agency’s technical capabilities.”

Said FTC Chairman Jon Leibowitz, “Ed is extraordinarily respected in the technology community, and his background and knowledge make him an outstanding choice to serve as the agency’s first Chief Technologist. He’s going to add unparalleled expertise on high-technology markets and computer security.”

An interesting observation, especially since cows’ … animal magnetism has been chalked up to wind and the angle of the sun for hundreds of years.