Dave Winer, often called the 'father of RSS' recently posted about a new Google service PubSubHubbub, that provides near real-time updates of RSS/Atom feeds. Per David it:
makes it possible to build a distributed Twitter-like system with components that are not made by a single company, and with servers not run by a single company. It makes it possible to build a Twitter without the limitations of Twitter. (For example, no 140-character limit, the ability to handle enclosures, categories without #hashtags.)
The protocol is free; anyone can run a hub or subscribe.