This feature is a great example of the kinds of things that are possible when rich social graph and user activity data is cross referenced and analyzed for patterns. There are countless different ways this could be done - but Friendship Pages aim right at the heart of why people use Facebook, for the connections it facilitates between family and friends. As with other changes made to Facebook, though, it's logical to ask: will this surface friends' activities that were always publicly available but become controversial once they are centralized in one convenient place?

The Man Behind the Feature

Friendship Pages is a very smart feature, something many of Facebook's users will find pleasing in a viscerally social way. The feature was developed under the leadership of Facebook engineer Wayne Kao, who made the announcement on the Facebook blog today.

Kao is an interesting character ("devastating and spiffy" is how he describes himself on his private Twitter profile). According to LinkedIn, he was the lead engineer at people search engine Spock.com for three years through the Summer of 2009. Spock was an ambitious search engine for people that burned through millions of dollars and then sold itself to the legally-challenged paid-search firm Intelius a month before Kao left.

Prior to that, Kao describes himself as the main PowerPoint coder on PowerPoint 2007 at Microsoft, a co-developer of the World Atlas at Encarta.com and the man who brought the world Dawsons.Creek.com, a 3 year long high-profile fan site of teenage schlock TV show Dawson's Creek.

Now Kao's built the new Facebook Friendship pages. It sounds like the coolest thing on his resume.

The Downside of Friendship Pages?

Every time Facebook creates a new feature that surfaces already public information, but in a newly convenient way - some people don't like it. When the very first Facebook Newsfeed took changes to already-visible profiles and centralized them in one highly visible place, people called it a privacy violation. (It's now the foundation of the site.)

Maybe that's not a big concern, but the unconsidered degree of closeness between many mutual friends is about to be splashed up on its own Facebook page for millions of people.

If you aren't doing anything wrong, of course, perhaps your social life has nothing to hide.

Meanwhile, the rest of us are going to have trips down memory lane made all the easier. If you're someone who uses Facebook to keep up with old college friends, friends you knew before there was Facebook, imagine how much more fun this will be for today's college kids. If they don't delete their profiles and start over upon graduation, these Friendship pages could prove to be one of the most emotionally meaningful parts of the site. And a whole lot of fun.

What cross-sections of the data on Facebook will be exposed next?

Next: Read Mike Melanson's argument - Facebook Friendship Pages are Just Plain Creepy

Agents are not permitted to friend suspected tax evaders using false information; however, public information is perfectly acceptable. In the past, collections agents were aggressive enough to appear at residences, places of work and schools. If you thought old school debt collectors were tough, think of today's social media wielding bunch as the Terminator 2 version.

While they're unlikely to kill your next-of-kin after questioning them, they can garnish your family's wages and slowly lure you out of hiding. If the group has just caught on to Facebook and MySpace, imagine the power they'll wield once they start using facial recognition software and people search engines like Spock and Pipl. You've been warned. Pay your taxes on time and avoid an audit.

Spock currently offers a public records search option to logged in users. In addition to the pictures, news, and web results Spock returns, public record data is pulled from USSearch.com. However, to get the details to those records, you still have to pay a one-time fee.

Privacy Concerns

Since its launch, many have people have raised concerns about how Spock operates. As noted earlier this year on Skiptease, there are several reasons to be wary of Spock, including the following:

1. Spock allows anyone to create and edit your personal information on the site, which raises numerous privacy concerns as well as concerns about the reasons people may have for editing your information on the site.

2. Editing or deleting information added about you does not guarantee that the changes will be made on Spock.com.

3. If you aren't informed that a profile or personal information has been added about you on the site, you might not discover the information until it shows up in a search engine query.

4. Even when your Spock profile is claimed by you, you still have little control over the information published on it. You can't personally get rid of any information and you have to request that the page be removed by the Spock search.

5. Turning a people search and social networking site like Spock.com into a wiki format where anyone can add and edit a profile on you allows people with a malicious intent to hijack your online identity and reputation.

6. The Spock people search allows users to flag inaccurate information. However, if you don't know that you are in their search database, there is no way to handle the information that has been published about you on the site.

On SEOMoz, after experiencing issues editing her own info, Jane Copland asked if a search engine that allows strangers to edit personal information about other people and then doesn't offer those people a quick way to remove the information they don't appreciate was "just a part of the internet we have to get used to" or if Spock goes a bit too far.

We found editing our profile information on Spock easy, though...that is, until an error message appeared which prevented us from continuing with the deletions we made. Afterward, we returned to our profile only to find that everything we had previously removed was still present.

With the upcoming public record subscription service, Spock has the potential to become even more of a privacy concern than before. By tying together your photos, web search results, social network profile info, and public record information, which invariably contains things like age and address history, we can see where Spock starts to cross the line from becoming simply a useful tool to one that starts to creep us out a little.

Do you agree? Let us know in the comments.

Note: we tried to contact Spock for more information on the service, but emails sent to the company bounced. Yikes.