In case any of the 7 regular readers here aren’t following xml-dev, check out and add to the discussion about Pragmatic Namespaces, proposed as a solution for the “distributed extensiblity” problem in HTML5.
For years people have been pointing to Java as the model for how XML namespaces should work, so this proposal goes that direction. Either it will work, or else it will get people to finally shut up about the whole idea. :)
It’s heavily based on Tom Bradford’s Clean Namespaces proposal, which doesn’t have a living URL anymore but is available on archive.org.