Communities of practice are forming with Facebook. Users with similiar interests are starting to link and connect to each other. Facebook recently opened its platform up to all users (it used to be for colleges only) and also opened its application platform up for anyone to create widgets or mini-applications within their platform.

For the marketer, the opportunity to extend to these areas are ripe: Join or build a community, deploy an application (widget), invest in advertising, gather intelligence from profiles, and extend one's network.

What you should know

• Invites via email spur growth: Invites are coming through emails. At one point, I was received dozens in one week; this is a sign of mass.
• Discussions: Within the groups sections, there are questions posed, answered, and discussed. If you're a believer in the Cluetrain manifesto; this is a sign of a marketplace.
• Business audience, not just 20s: When Facebook opened up to the whole world, it extended its reach past college. This may have been due to many of the original Facebook users graduating and moving into the workplace. Many of my contacts and friends within Facebook are senior managers, directors, VPs, and CEOs—this is not child's play. Recent research indicated that the fastest growth segment was 35+. See my Facebook demographic and audience analysis.
• Affinity groups: Individuals with similiar interests, problems, or traits are starting to self-assemble through their friends network, or within the groups. All of these are opt-in, so these are engaged users that have self-selected: "Hey I belong here." These are communities, and are micro-segments of marketplaces.
• Opt-in: Unlike traditional forms of advertising and marketing, Facebook has many opt-in features that let users review, approve, and accept invites for friends, applications, groups, and other features.
• Limited search crawling: Facebook is a "closed" network, and you can only see most data if you've a login. Most individuals' pages are somewhat private to non-friends. As a result this limits the ability of traditional search engines like Google, Yahoo, MSN, Ask, and others to crawl and index the data. This will prove to be an interesting dynamic in the next few years.
• High growth: Facebook has one of the fastest growth rates, and could potentially overtake MySpace if these rates continue. See stats from John Bell.

The Platform

• Identity platform: Facebook has opt-in user profiles and rich metadata, they've massive intelligence on users. Similarly, users can see detailed metadata about friends that are connected to them. Traditonally, blogs, forums and other tools don't provide this detailed amount of user data.
• Community platform: Users can connect to affinity groups, Facebook can map relationships and affinities. Communities are forming (all opt-in) and are segmenting by interest. "Community" is another word for "market."
• Application platform: Facebook controls API platform and can gain intelligence from application deployment, data, and usage.
• Clunky user interface: Facebook is notorious for being confusing for the early and even experienced user, things are often not where they should be, and it's difficult to tell where one's "homepage" is.
• Homepage: The homepage is really a "news" page that aggregates content like an RSS feedreader. It also shows other events, triggers, requests, and information; this is much like the portal page of the first wave. You can adjust the settings to increase or decrease certain types of content. You can also see what your network is doing, including your friends writing on others' walls (there was conflict about this previously). The homepage can also show updates from applications (like Twitter or Pownce) centralizing communications.
• Profile page: The profile page lists your attributes, status, interests, and other metadata a user chooses to share. This is the page to share with others to add them as contacts.
• Applications: The applications section has exploded from hundreds of applications a few weeks ago to thousands. As I understand it, a PHP developer can quickly create an application for use there. In some cases, brands with loyal following have customers create applications on their behalf.
• Events: Affinity groups are starting to organize, promote, and manage events from Facebook. (For example, Ann Handley listed the MarketingProfs upcoming B2B Forum there.) This is disruptive to Upcoming, evite, and other event management websites.
• Direct messages: Users, and those in my community, are starting to direct message each other using Facebook's "email" type of capability. There are numerous accounts that users in Gen Y use social networking private messages before email. In fact, I'm told that "email is for old people, like you."
• Media is embedded: There's audio, video, and live streaming video in Facebook; this is a communication and media platform. There are many ways to embed stories using rich media.
• Widgets and applications: The most exciting feature are the widgets that let companies and groups build embedded applications on the Facebook Platform. While widgets have certainly been around for some time, they've never been available for an "identity" platform that had rich user and network behavior.
• Case study: Watch how Wal-Mart's Dorm Room campaign is now deploying an application for Facebook, Charlene Li predicts opportunity, and John Bell is keeping a watchful eye. If you don't know the history, Wal-Mart launched a MySpace clone called "Hub" which failed and was shut down after a mere 10 weeks.
• Advertising: There are embedded ads within Facebook on the right column (and other areas) which give the savvy advertiser ability to reach specific markets. Because Facebook is an Identity Platform, they've got full data and stats on what users are doing, how often, how much, and what they are doing. Learn more from the official advertising page.

Data and Privacy Concerns

Facebook is a black hole, a lot of data goes in, but very little comes out. This is yet another reason why we need a single trusted, and protected identity system. What's more, all your widgets are belong to Facebook.

So—where do you get started?

1. Understand Facebook.
2. Jump in and create an account.
3. Explore the groups.
4. Explore the applications (on the left nav); see how they're used, and add a few of your own.
5. Consider your strategy, and perhaps find a partner to help.