Dear Gaven,
OpenACS doesn't have exactly what you are looking for out of the box, but all the building blocks should be there.
- chat package: this allows to create chat rooms where allowed users can communicate in real time. It is based on a Comet implementation. [1]
- forums: this package implement the forums we are writing on right now 😊 [2]
- notifications: it's a component that can be used by other package (like forums does) to subscribe to events happening on a particular object on the system and generate a reaction (typically some email being sent, but can be extended to whatever reaction through callbacks). This package is the one implementing the "Request Notifications" feature in this forum. [3]
Something else you might be interested into is websocket support in NaviServer, which can be used to implement a chat as well. Currently this is not used in any OpenACS package, but a demo implementation of a chat is there to use as a reference [4]
Hope this helps
Antonio
[1] https://openacs.org/xowiki/chat
[2] https://openacs.org/xowiki/forums
[3] https://openacs.org/xowiki/notifications
[4] https://bitbucket.org/naviserver/websocket
