Microformats aside, I'm trying to understand the solution to the hub part because that sounds like a problem many people would be interested in fixing.
The reasons to do that are laid out in my blog post but the most important is consistency. If one piece of JavaScript gathers the data once and passes it to various vendors, then you know that the same data was sent, and was actually sent.
You'll probably find that most of the requests you saw in Firebug are for the Inspector tool (built using YUI2).
The jshub.js file is the only 'tag' needed on a website (+ jquery if not already in use) and is designed to provide a 'hub' API for each vendors plug-in to query the data collected and send it on its way to a receiving server so only one file need be maintained as vendors come and go.