For a web-application I am writing (Rails) I am looking for ways to post back publick mentions about that post. Mentions on Twitter, Facebook, Reddit and so on.
Starting with Twitter, I am looking for a way to get these tweets back into the application. Obviously I could simply monitor the twitter firehose (through their search, most probably) for a certain url (the url of the post), if found, extract that and place that tweet as new comment to the post. But this requires me to invent something similar for each and every social network.
Whereas there is a generic protocol for this: Salmon, allowing services to push such comments (tweets mentioning your url) through PubSubHubbub (PSH).
I did not find any mention of this on the Twitter API itself; they are not using PSH or Salmon (yet) it seems.
But maybe there are thirdpartis that do? Know any? Are there other projects that wrap around Twitters firehose and allow you to approach Twitter as if it is a Salmon-speaking pubsubhubbub? And What about Reddit, or Facebook?
The Twitter API TOS explicitly forbids the re-distribution of tweets via APIs*, except for Twitter's partners. These are DataSift and Gnip - but they don't do what you are looking for.
Your best option would be to simply monitor the filterhose.
* Actually, it's allowed to share IDs, but those are pretty useless since you have to look them up manually.