After the Fork
The prediction that different formats would confuse the marketplace has proven to be incorrect. On the contrary, RSS adoption rates have increased since 2002, with RSS readers supporting both the RSS 1.0 and 2.0 specifications equally.
Aggregators such as Radio UserLand (Windows or Mac), NetNewsWire (Mac only), and NewsGator (Windows only) support all the formats, which simplifies the decision of which format to implement. Recent changes to the RSS 2.0 specifications have allowed for support of namespaces, which means that the extensibility of RSS 1.0 is no longer a core advantage. As a result, implementing RSS 1.0 feeds instead of RSS 2.0 is only necessary if the feeds need to be integrated with other RDF applications.
In August 2003, Dave Winer and UserLand agreed to release the RSS 2.0 specification under a Creative Commons Attribution/Share Alike license, which means that you're free to build anything you want on top of the specification as long as you credit the original authors and allow for redistribution of your changes in the same fashion. This setup has the potential of breathing new life into the format.
Microsoft has already sworn support for RSS 2.0 in Longhorn, announcing that the new Windows operating system will support the specification as a core operating system service.