WorkBook is apparently part of the WorkLight platform, and pricing starts at $10/user/month.

Some coverage:

• WorkLight secures Facebook for enterprises (Dan Farber on ZDNet blog – with a photo)
• WorkLight enters the Enterprise Facebook Market (Bill Ives at Fast Forward Blog)
• WorkBook: Getting Facebook Ready for Work (Andrew McAfee)
• WorkBook Brings Facebook Inside the Firewall (Web Worker Daily)

McAfee, who was able to see a demo, has the best details on the workings of the app:

In a quick demo, Lavenda opened up his standard public Facebook profile, then launched WorkBook (Worklight’s offering) just like he’d launch any other Facebook application. After he logged in, a separate section opened up within the profile. This section was devoted to the user’s employer— let’s call it Lavendaco. Inside this section were a number of standard Facebook features— friends, groups, Q&A, profiles, etc.—presented using the standard Facebook UI. But the data populating each of these were specific to Lavendaco, came from the Worklight server installed at Lavendaco, were encrypted as they travelled across the Internet, and did not pass through Facebook servers.

But I have to confess my own reaction is closer to Bill Ives, which is, wouldn’t this be pretty easy to build yourself, on top of Facebook APIs?

Maybe a good candidate for our next ONE (Optaros New Employee) training class, wherein the team does a quick project. Our Intranet is Drupal 6 based, and shouldn’t be too hard to pull that in to Facebook. I know there is already a Facebook Module for Drupal 5.x