RSS was first invented by Netscape, when they were trying to get into the portal business. They wanted an XML format (RSS .90) that would be easy for them to get news stories and information from other sites and have them automatically added to their site. They then came out with RSS .91 and dropped it when they decided to get out of the portal business.

UserLand Software picked up RSS .91 and continued to develop it, coming out with .92, .93, and .94. At the same time as UserLand, a non-commercial group picked up RSS and developed RSS 1.0 based on their interpretation of the original principles of RSS. They based RSS 1.0 on RDF and re-named it RDF Site Summary. UserLand was not happy with RSS 1.0, and continued development of their version of RSS (Really Simple Syndication), eventually releasing RSS 2.0.

Source: http://webdesign.about.com/cs/rss/a/aa052603a.htm