APIs and Facebook Connect
Robert Glass, Hanni & Rebecca asked, "What is an API? Where can I get one?"
API is an acronym for Application Program Interface. When a software or website features an API, it provides a means by which other programs can directly interface with it to perform additional functions.
Twitter is a site where people post their current status so that friends can follow what they're doing. The Twitter API is very popular as it permits those status updates to be added by other software programs. This means Twitter users don't always have to use the Twitter website to view and change statuses. The result is that many desktop and mobile software applications have been written by people without a formal relationship with Twitter. Since the Twitter API allows for adding, updating, searching and deleting all status updates, you can reproduce what the website offers, integrate Twitter into a website or go further by creating new functionality that didn't previously exist (e.g. allow users to add photos and video to their status updates).
Social networking sites like Facebook and MySpace have extensive APIs. Online applications like Google Mail, Google Maps, etc, all have APIs as well. Social Networking sites like Facebook are becoming increasingly open which means making their data easily accessible. The implication for you is that a private social network, though separate from existing networks, doesn't have be an island. It can tap into and talk to nearly ever other social network out there if were programmed to do so. It can also be made to connect to your corporate systems in the same way.
Related to this is Facebook Connect which is brand new and gaining in popularity. It's a way of integrating your site with Facebook without having to make a significant investment in programming. For the most part, it hides the complexity of their API to enable Facebook users to re-use their identiy on your site. Once you have someone's Facebook ID and they've granted your site permission, you can begin to tap into the wealth of information they store about that person. Read more about it on the Facebook Blog.