One of the big changes that will be enabled by the coming Metaweb is the shift from application-centric computing to data-centric computing. As the Metaweb evolves, information will be imbued with increasingly sophisticated metadata. HTML provides metadata about formatting and links. XML provides metadata about structure and behavior. RDF, RDFS and OWL provide metadata about relationships and meaning.
As higher levels of metadata are adopted and added to content, the content becomes "smarter" -- more information about how to display, use and interpret the content is added to the content itself. The key here is that this metadata is added in an application-independent manner. In other words, the "intelligence" for interpreting the data is moved out of applications and into the data itself. Thus we move from "smart applications, dumb data" to "smart applications, smart data."
A data-centric world will be very different from the application-centric world of today -- for one thing, application providers will lose much of their competitive advantages (from platform lock-in and closed formats) as data becomes increasingly portable across various tools. Another big change will be in how we think about content -- rather than content being thought of as static documents, every piece of content will be more like an object with its own unique identity and behaviors on the network.
Instead of moving data around we will access these semantic data objects using Web services protocols and interact with them from anywhere like mini-online services. To edit a document we might send commands to an object that represents the document on the network, rather than actually downloading and modifying a local file.
Ultimately this will bring about a shift from desktop computing to network computing -- software will truly become a service and the business model of software will shift to be more like online service business models -- based on subscriptions, a la carte pay-per-use features, and perhaps even advertising. Data objects will be accessible from everywhere and will be responsible for maintaining their own state, relationships and contents, as well as managing their own access, rights and usage policies. These are some of the changes that will come about as the Metaweb evolves.