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.
Now, how will RSSCloud compare to PubSubHubbub? As Chris Messina points out on a comment to Dave Winer’s announcement, “it’d be nice to either protocol gain adoption and enable a better P2P push-based infrastructure to rise up.”
Let’s see how both technologies evolve. So far RSSCloud is only being used by a single feed reader but has gained a massive number of publishers through the WordPress.com adoption.
PubSubHubbub is ahead in the game, currently being used by Feedburner, Blogger, Google Reader, Google Latitude, YouTube, PicasaWeb, FriendFeed, LiveJournal and Superfeedr, to name just a few. There’s also a WordPress.org plugin, written by Josh Fraser.