2Entwine's brief tutorial on the PubSub query language hints at the power of a real-time matching engine, basic query language, and push capabilities. With PubSub, you really can watch the conversation around your own or others content.
The only downer is that programatically, to tie into PubSub you need to use a protocol layered on top of XMPP. I spent a good chunk of this afternoon looking around for a way to conveniently hook in using Python, but only found promising leads, not four square hits. Maybe other XMPP/Jabber language bindings will work better, but that was a bit disappointing given the age of Jabber Publish/Subscribe.
idavoll looks like a viable alternative, but I've been trying to avoid the Twisted inhale.