Salmon, an aggregation protocol, is championed by Google’s John Panzer, and described as an “an open, simple, standards-based solution” for “unifying the conversations”.

‘Conversations’ is deliberately plural, I think, to evoke the many conversations, invisible to one another: “The comments, ratings, and annotations increasingly happen at the aggregator and are invisible to the original source.”

Using Salmon, an aggregator pushes comments back to a “Salmon endpoint” (via POST). These can be published (or moderated) upstream at the original source. See also the summary of the Salmon protocol.

Comments swimming upstream…