Rambling about application flow, I think that the general outline will
always be like this:

1) you're on a web page with something you want to reuse. We're using
"reblogging" as a convenient shorthand for reusing stuff from a web page.

2) you grab the stuff, either with something like a Greasmonkey-based
microformat parser or by clicking a link provided by the source page.

3) you send the stuff to the correct handler by using something like
OpenURL, the Redirect This web service, or a MIME helper app.

4) the handler applies format-specific knowledge to the stuff (like an
editor for hReview) and helps you route it to the final destination.
This is where output-this fits in. I think that reblog.org also fits
here, but I'm not sure.

5) the final destination publishes the stuff, for example by posting
it on a blog. An example final destination is a Wordpress
installation which receives data via the Atom API.