The changes to the Specification are as follows. This list of changes is also listed in Appendix B of the specification, Errata.
1. The RDF/XML version of the RDF Schema and OWL Ontology, ont.rdf, is now the normative version instead of the Turtle version. 2. Encoding of documents has changed from having to be one of UTF-8, UTF-16, or UTF-32 to allowing any encoding but recommending UTF-8. 3. Mentions of US-ASCII have been removed as redundant. 4. Use of RSS 0.92 as an example in the motivation section as been changed to RSS 0.91. 5. All keyword MUSTs in section 4 have been changed to to musts. 6. The OWL cardinality constraints are now datatyped with xsd:nonNegativeInteger. 7. All OWL qualified cardinality constraints have been split up. 8. rss:item/@rdf:about has been made mandatory. 9. :Image/:link is now optional in the RDF Schema and OWL ontology. 10. :URI is now an instance of owl:Class. 11. Cardinalities of 1 have been changed to minCardinality. 12. Introductory mention of "up-to-the-minute content" has been changed to be less restrictive. 13. The RELAX NG compact schema now uses content groups for reusability. 14. The erroneous grouping constraint, only noted in the changes appendix, has been removed. 15. rss:image has been added as a property to the RDF Schema and OWL ontology. 16. Leigh Dodds's status suggestion text has been incorporated. 17. The applicability of xml:base is now fully specified. 18. More information has been added on the semantics of rss:item/rdf:about. 19. Attributes in no namespace are now disallowed in Any sections, reflecting a constraint of RDF/XML. 20. A non-normative maching readable mappings to RSS 1.0 appendix has been added. 21. The RDF Schema and OWL ontology now uses annotation properties. 22. The OWL Ontology is now in OWL Lite instead of OWL Full.
Just noticed that I never made it clear that this is an outside specification. It is incompatible with all other formats as it has a root elememt 'channel' and other incompatabilities.
"... our intention has been to ensure that producers of RSS 1.0 have minimal upgrade impact, which means that we're not opposed to people having a harmless url element lying around. RSS 1.0 requires it, so RSS 1.1 deprecates it. We can always remove it in RSS 1.2."
Two aggregators, BottomFeeder and JabRSS have already added support for it.