I've been lately interested in the AS 2.0 spec. I think projects like OStatus are going to move away from the verbose nature of XML Atom feeds in favour of JSON ActivityStreams.
So one thing I've been wondering about is, how do you link to a PuSH hub in an ActivityStream for example? There has been discussion in this thread
, but after briefly looking at the specs, there doesn't seem to be any standard manner for including something like: