When you confirm a new friend, you'll be presented with four people that friend is connected to - four suggestions for people who might be mutual acquaintances based on your social graph. It's more useful and more accurate than the current friend/fan suggestion feature, and we actually like it a lot. Check out the screenshots, or try it for yourself the next time someone friend requests you.

I realized that I did, in fact, want to be connected to quite a few of these people because our social graphs do have quite a bit of overlap and we've met in person or online. Some of these recommendations, such as Tara Hunt and Sarah Austin, popped up several times as they were mutual friends of more than one new friend I'd just confirmed. Smart tech!

"We are still testing it," wroteFacebook rep Kathleen Loughlin in an email, "but we've found that Facebook is a more valuable experience for people when they are able to find and connect with their friends. While we already have a variety of tools to help people connect, we've started experimenting with ways to make these tools even more accessible and easy to use."

We particularly enjoy this feature because it gives a more tangible reason to reach out to a new friend than the easily ignored "mystery people" column on the right side of the screen. Sure, they might have friends in common with me, but which friends? What social groups are they part of that relate to what I'm doing? Making and finding friends this way can require a bit of digging around, for example, realizing that you've actually met the person before because you go to the same conferences. So it's not ideal for at-a-glace suggestions sometimes.

What do you think of the new feature? Is it helpful or not for how you use Facebook and how you define or filter your Facebook friends? Let us know what you think about it in the comments.

Also, if you've got a moment, check out RWW's Facebook page! We'd love to have you as a fan.

You'll find them below... but they're only a starting point. Kindly add yours in the comments, and maybe - just maybe - they'll be coming soon to a form field near you.

More Noise to Signal.

1. Mutual reinforcement of user expertise and document quality: A user's expertise in a particular topic depends on the quality of the documents she or he has found, and the quality of documents in turn depends on the expertise of the users who have found them.
2. Discoverers vs. followers: Expert users should be discoverers - they tend to be faster than others to identify new and high quality documents...SPEAR gives more credit to users the earlier they find high quality documents.

After analyzing more than 500,000 Delicious users and 2 million shared bookmarks, the solution produced a set of trustworthy users. No spammers were found in the top 200 recommendations.

While there are obvious uses for SPEAR in shopping and friend recommendation engines, says Noll, "The SPEAR algorithm itself is not restricted to the online world. We imagine to use SPEAR, for example, for estimating the expertise of researchers by analyzing scientific publications. Such publications - whether available as online versions or printed out on paper - provide all the information we need."

Expertise may have an algorithm across all industries. Be first and be fascinating. For more information on SPEAR visit Michael G. Noll's site.

Based on this data, Marlow argues that once your network grows beyond the Dunbar number of 150 (the theoretical cognitive limit of how many people one can maintain a stable social relationship with), you are, at best, increasing the number of 'casual contacts' that you track passively.

What About Twitter?

Marlow, of course, focuses only on Facebook, but these numbers are also quite interesting in the context of other social services like Twitter. Just this week, we saw a an interesting discussion about how many followers one can really interact with on Twitter - especially considering that some users there follow tens of thousands of people.

While some of these numbers for Facebook probably also hold true for Twitter, it also needs to be acknowledged that Twitter is a far more casual network than Facebook, where users just dip in and out of the message stream during the day. Also, the concept of 'friendship' in general also seems to be more loosely defined on Twitter.

But if you really wanted to have a two-way communication with most or your Twitter followers, then following 10,000 people is simply crazy. However, those Twitter addicts who follow this many users probably also only really track a very small subset of their followers through groups on Tweetdeck and searches.

1. Me. Access books, music, movies, restaurants, wine etc. that you liked and commented on via the browser. All your favorites are always synched up and right there when you need them.

2. Friends. When you're looking for social recommendations on the go, you can tap into an intelligent, aggregate list of things your friends liked around the web.

3. Popular. This screen lets you expand your circle and stay connected to what is happening on Glue around the web. You'll find 100s of books, music, movies, restaurants, wines and more that are popular among the Glue users.

As you browse through the items, you can either display them in the standard view as shown above, or you can switch over to a more fun "cover flow" view that allows you to quickly flip through the different films, books, restaurants, etc. similar to the way you browse through your albums on your iPhone/iPod.

The iPhone app is definitely a must-have for Glue users as they will enjoy having access to their friends' recommendations even when they're away from their computers.

"Microblogging services like Twitter break down if you have more than 100 followers," wrote Carson. "People like Jason Calacanis might disagree, but I'd argue that by him following 26,672 people he's obviously not actually interested in what those people are doing (nor would it be possible to actually interact meaningfully with them)."

But why limit it to microblogging -- can we really keep up with thousands of "friends" on any social network? Could we do it in offline life?

Research by Robin Dunbar indicates that 100 to 150 is the approximate natural group size in which everyone can really know everyone else. "Human beings ought to live in groups of around 150 people, judging from the logarithm of our brain size; and sure enough, studies of hunter-gatherer groups, military units, and city dwellers' address books suggest that 100 to 150 is the natural group size within which people can know just about everyone directly," writes Jonathan Haidt in the book "The Happiness Hypothesis," drawing on research by Dunbar.

Last summer, we asked readers how many Facebook friends they had. The vast majority had under 500, and 45% had under 100. It might be that most people naturally limit the number of friends on a service to a group that they can realistically manage. Most people don't have the time to actively manage a network of a thousand or more friends, anyway.

Consider this and let us know in the comments: How many friends do you have at your favorite social network? How many of those people do you have regular, meaningful interactions with? Does there appear to be an upper limit to how many online relationships you can manage?