In fact, I would like something like “real time”. To be notified once a change in a note is done.

Parsing the planet is what I have already done, but this process is very slow (processing the whole XML takes a time) and this daily periodicity is not what I am looking for.

(Pull notification) I can create a RSS for the whole world, and polling it each minute, but this impact the API, because many of the feeds will not contain any new value. This operation is started form the requestor. My view is that if everyone is polling the API, the server has to respond these requests. I want something real time without huge impact, or unnecessary CPU cycles. I would like something different that: “Hey API, is there anything new in this area?”

(Push notification) I would like to “receive” the notification from the API, once I have subscribe to it. To receive from the server when there is something new. This operation will be started from the server.

Probably, the current API status does not provide subscription like this, and I will have to use the API by polling it periodically. It could eventually be part of the API 0.7.