Interesting. Is this actually real-time, or are you just frequently polling feed urls from a central source and then pushing them to the clients on a case-by-case basis? I'm assuming the latter, since the former has traditionally required participation on the part of the feed provider, in the form of something like Google's PubSubHubBub.
it's real-time when possible (if the publishers are using PSHB) otherwise it is polled as timely as possible. most posts come through within a few minutes of being posted.
