Openfire is an RTC server that manages chat rooms. The REST API sends HTTP requests to the server and in this case, the PHP library facilitates the access to the API. Once users access the API with HTTP and shared secret, they will be able to retrieve, create, and delete users in chat rooms. They will also manage groups of chats. Installation and usage guides available.
PayPal, looking to provide an additional structure around the Node.js application framework, developed the Kraken implementation, a more secure and scalable framework for building commercial-grade applications. This week, PayPal is making Kraken available to the broader open-source community.
PubSubHubbub. Say that three times fast. If you're not familiar with PubSubHubbub, it's an extension of the RSS and Atom protocol that allows the feed to push content out when it's updated. That's just the sort of technology we should see from check-in APIs like Foursquare and Gowalla.