Remember what the web was in 1992: a way to share textual scientific documents. How does that change anything? All you can do is change the display format. ;-)
And then people discovered you could embed images in these documents. And you could sell stuff by listing the stuff you had for sale and having people send you money. And you could hold auctions with them, once they figured out how to let you update the page automatically. And you could upload pictures of your dog and send them to friends.
And then folks realized that you could include a scripting language on both the client and server, and let computers handle what website operators had been doing. Update webpages through a form. Let people talk to each other on forums without the webmaster getting involved. Automate those online auctions. Display your email. Search for maps and driving directions. Look for the multi-gig files that were previously available on CDs, and download them via BitTorrent.
So, microblogging. Companies are already Twittering product announcements and special promotions to customers. What if the customers could Twitter back with suggestions? What if they could buy it immediately? What if you could Twitter a picture or a song to your followers and they could listen immediately, wherever they were (isn't Pownce doing that?)? What if someone did a bot that monitors Twitter for mentions of your product, then ran some NLP on them and sent you neatly categorized suggestions for improvements? What if someone clustered Twitter users with some clique-detection algorithm and used that to segment markets?
Hot damn, I may've found my next startup idea. Or maybe I should just apply for a job at Twitter. ;-)
I really don't see how this is useful. Maybe I've become one of those guys who doesn't 'get it' anymore, but I think that twitter is not going to be as big as you think. Yes, a form of mini communication will happen, but in the current form, there will very quickly be too much information. We have finite capacities for processing stuff, and twitter is a rabble of information, which just gets wearying after a while.
To me, the people who are really into twitter all seem to be the same demographic, and that's usually bad news for a technology. It's those same people who used to like Usenet and the IRC that are now using twitter.
Twitter is something that intrudes on your life, and having it does not solve any problems, it adds stuff to what you already have.
But I won't protest too much, because it's possible I'm wrong on this one. I'll just wait and see. But frankly, I still don't see how I could somehow get my mum excited about twitter, even if it had all those features you spoke about.