How will Echo support ad hoc extensions?

Two ways, I think. Sort of. The way the specs read now...

Just Add It. Echo files will be well formed XML. And will be parsed by XML parsers. So you can extend an Echo file with any XML you want. If the reader doesn't understand it, it is free to ignore it. Add your XML fishing report (ns:bass length="thiiiiiis long").

Just Point To It. You can also include by reference. Write about the fish in your post, but the structured information is outside the syndicated feed, described with a link to the location and a reference to the type of object you might find there.

This feels like an abdication of extensibility.

I want more than Just Add It And Hope For The Best. I want an envelope, a wrapper spec, that helps tool developers encode new package types and read them. Echo's mechanism is the ExtensionModule. 

extension modules have a UniqueIdentifier and a DefinedDataModel

Neither are defined. Bill Kearny's great backgrounder on UniqueIdentifier isn't a spec and DefinedDataModel is also a placeholder.

Here's hoping we can muster enough attention to get these two parts spec'd.

p.s. I'd appreciate your contributions, pro or con, to the Component Blog and Adaptive Blogosphere wiki pages.

p.p.s. ZenKai's blog reminded me that Jon Udell used the term "Semantic Weblog" back in April 2003. Jon's examples asked a weblog questions about its posts. I'm not sure the Echo replacement for the metaweblogAPI includes those abilities. Anyone?

Christopher Saunders writes a great roundup of the integration and convergence of instant messaging and blogging for IM Planet. IM is used for posting to blogs, update notification, and reading blogs. With AOL offering their Journal products, expect all the blogging vendors to emphasize blending blogs with messaging media: IM, SMS, MMS, voice mail, and email.

Thanks to Bill Vick for the link.