To be able to give a user the address of the exact information they want means breaking down monolithic content like video streams and calendars and forum threads. And that means thinking about how things are indexed, and they they're presented. When Blinkx finds a video that matches what you're searching for it could send an offset to start the video playing at the right point - but content owners don't like that because they've put the ads that pay for their service at the beginning of the video. Too many groupware systems give you a link for the calendar, not a link for individual days or events in the calendar. And if a link to a forum comes up in a search you'll usually find yourself at the first post in the thread rather than the relevant post - the whole thread has been indexed rather than the individual posts.
What's the logical addressable unit of content? It's going to vary depending on the content type, but as a consumer I'm going to want more granularity than the producer expects. Often, there's a fragment of information that's exciting or interesting that I want to share rather than pointing someone at a whole work; I'm hoping they'll find the whole thing interesting, but it's the snippet I think will catch them. The smart content provider will see value in letting me push people to the interesting bit in the hope they'll want to see more rather than forcing people to sit through all of it. Addressability might look like losing control - actually it's giving both publisher and visitor finer grained control.