But then it occurred to me that maybe doing cut and paste from webpage A to webpage B is a missing feature.

I dont think microformats or frames answer this need well.

It seems the most basic feature of a web mashup, so why dont we see this as a trivial standard?

<div src=url id=div_id />

Ive used plone before as a companywide repo for project docs, but one feature I wanted was to do this for subsections of a page. This would have solved that problem.