I have evalgalised for a while the innovation that is unleashed in clients and servers when a standard format exists for passing information beteen them. RSS is a great example of this, and Dare makes the point strongly in this article, a snipit from which reads:
RSS is a wonderful example of the higher level of interoperability that can be built upon XML formats. Instead of information sources using various incompatible mechanisms for providing information to end users such as NOAA’s SOAP web service and the Microsoft.com web services which each require a separate custom application to consume them, sites can all standardize on RSS. This standardization creates an ecosystem of applications that produce and consume RSS feeds which is a lot larger than what would exist for each site specific web services or market specific XML syndication formats. Specifically, it allows for the evolution of the digital information hub where users can view data from the various information sources they care about (blogs, news, weather reports, etc) in their choice of applications
He goes on to point out that RSS goes one better by allowing domain specific extensibility whilist still allowing standards based readers to consume feeds:
Additionally, RSS is extensible. This means that even if the core elements and attributes do not satisfy all the requirements of a particular problem domain, then domain-specific information can be added to the feed. This allows for regular consumers of RSS to still be able to consume the content while domain specific applications can give users a richer experience. This is a much better solution for both content producers and consumers than coming up with domain specific applications.