“All blogs on the WordPress.com platform and any WordPress.org blogs that opt-in will now make instant updates available to any RSS readers subscribed to a new feature called RSSCloud. There is currently only one RSS aggregator that supports RSSCloud, Dave Winer’s brand-new reader River2. That will probably change very soon.”
By “change very soon,” Marshall Kirkpatrick (who wrote that post) is suggesting other publishers of RSS feeds (and the newsreaders, etc., that read them) will likely follow WordPress.com in supporting the <cloud> element which, according to Dave Winer, first appeared in January, 2001.
Without getting too technical (something that would require me to actually understand how it works), this means that blog posts (or anything that is published to an RSS feed) can be distributed with the real-time speed of Twitter tweets or text-messages or Instant Messaging.
While you may not recognize the current delay between when a post is published and when it shows up on your (virtual) doorstep, you will during the next breaking news event if you see it being covered in an online story that is being updated tweet-like, sentence-by-sentence, in realtime — with no concern for the 140-character limitation, or lack of media attachments, that make Twitter less-than-optimal in providing paragraph-length information.
Bonus: Matt Mullenweg officially announces the WordPress support of RSSCloud.