Every two minutes, FooCam takes a photo of the lab and uploads it to the web.
The Mac runs a script in the background that takes a photo with its iSight camera every two minutes. Once the photo has been taken, it gets uploaded to Dropbox (replacing the previous photo). The Dropbox folder is public, and also contains a webpage that shows the latest FooCam photo. The combination of these things means that users can visit the webpage and quickly find out who is currently in the lab, all without disturbing the people in the lab. Having a photo updated every two minutes balances the need for up-to-date information and the privacy issues that a solution like a continuous audio/video stream would present.
If one FooCam photo is particularly interesting, users can click the Fave button. This posts the current FooCam photo to the FooCam Tumblr (with an optional caption). Because of this, the FooCam Tumblr acts as a kind of archive of particularly funny or interesting FooCam photos.