Facebook has introduced "custom tags," a way for application developers to share small segments of functionality and/or content with other developers.

Developers simply embed the tags into their existing code, which on the Facebook platform is easier than using JavaScript widgets.

Others can then reuse those blocks of code and extend the features to their applications. For example, the Graffiti app could let other applications draw designs for specific events, or Catbook — using the Causes donation widget — could enable user donations for animal causes.

"I’m sure we’ll see new types of cross-application functionality," Josh Elman told AllFacebook.

When custom tags are enabled for Facebook Connect-powered websites — which Facebook promises will happen "soon enough," there will be a significant increase in widget adoption, Facebook projects.

A Facebook Connected New York Times website could, for instance, put a Visual Bookshelf widget on its Bestseller books page so readers could immediately see which friends are reading what books, as well as their opinions and other relevant information.

Such cross-functionality may ultimately increase Facebook’s strength as a communication tool for marketers. Third-party sites like Viewpoints already make Facebook apps that let members post reviews and recommendations for consumer products within Facebook itself. And those words are more likely to influence purchase decisions within that person's network than on an external review site, AllFacebook writes.

The commercialization of Facebook, however, is touchy subject. When Facebook's Beacon was introduced, for example, people protested that it invaded their privacy. (Beacon enabled friends to see what other friends purchased on sites like Fandango, Overstock and Blockbuster.) Facebook responded accordingly.