In a nutshell the Metaweb is not a new Web, rather it's a new evolution of the existing Web comprised of interconnected microcontent objects. Let's unpack this definition.
The Metaweb contains the Web
The Metaweb is not a new Web, rather it is the next evolution of the existing Web. The Metaweb includes the first Web (Web sites, Web pages, files and servers) as well as other Internet resources and even resources on computers, cell phones, PDAs and other connected devices. It might be useful to think of the first Web as "Web1" and the Metaweb as "Web2" -- Web2 contains yet extends Web1. The Metaweb is the first step towards the future "Semantic Web."
The Metaweb is a distributed network
The Metaweb, like the Web, does not exist in one place. Rather it is a distributed system that is chaotically organized from the bottom-up in a grassroots manner.
The Metaweb is comprised of microcontent objects
What is a "microcontent object?" Here is one attempt at a definition: It is a finite collection of metadata and data that has at least one unique identity and at least one unique address on the network, and that encapsulates no more than a small number of central ideas, where the number of central ideas encapsulated is usually 1.
For example a Weblog posting is a microcontent object because it is a finite collection of metadata (the fields of the posting as defined in XML or RDF) and data (the content of the posting), and it has an identity and URL, and is generally focused on providing a small quantity of information about a single central idea (although not always).
Contrast this with the concept of a "Web page" or a "Web site" and the distinction becomes a little clearer. A Web site is a complex, compound collection of metadata and data that may be addressed on a single domain-name, and that contains one or more information collections of unbounded size where each sub-collection may itself comprise a Web page or another Web site. A Web site is therefore "macrocontent" rather than "microcontent."
A Web page on the other hand is a little closer to the micro-level, but even here there is still a distinction between a typical Web page and true "microcontent" -- namely that a Web page is not limited to being "small" or to being focused around only a few central ideas (for example, consider the home page of Yahoo -- this is a page but it is not microcontent).
Microcontent is a new class of content
Microcontent is "small content." That is, small, granular pieces of content, each with an unique identity and URI, that may be published, subscribed to, and linked across the network.
Examples of microcontent include typical Weblog postings, RSS/Atom posts, discussion postings, Wiki nodes, or database records that have their own URI's.
If anyone would like to help to refine the definition of "microcontent" here, please feel free to add comments to this article with your suggestions. I admit my definition could use some work, but it's functional at least.
One important point that is worth debating: How essential is metadata to microcontent? Can microcontent exist without containing metadata or is metadata the key to microcontent? In my definition above I suggest that metadata is a requirement of microcontent, but that may or may not be the case. Is the definition of microcontent merely that it is "small content" or is it "small self-describing content"? What do you think?