Take a hypertext link, some ajax and a little Jquery and shake them up and you get a sample of what a transaction might look like in the Twitter stream. This is just a sketch, a visualization, of one way placing your cursor over a hyperlink that might expand into an offer that you could respond to with a single click.
In the sample Twitter page below, go to the first entry and place your cursor over the hyperlink in the first Tweet.
Add to the list of Twitter’s possible business models: a proprietary URL shortener that expands into a special offer. Just a thought.