Microformats are an easy way to semantically mark up a web page so that it can be easily parsed and understood by a computer.
This allows you to write code to easily do many funky things, not least of which extract author information from a page with minimal effort. This is how Idno’s distributed friending functionality works, btw.
Idno/Known supports MF2 natively, but support was sadly lacking in Elgg, so I wrote a quick plugin to add it.
The plugin, once installed and activated, adds some hidden markup to certain core views and does some basic post processing to add MF2 markup.
It is designed to be as light weight as possible, while still providing useful functionality.
As I mentioned above, and in the readme, this was primarily written to scratch an itch – namely, to provide the base functionality for Idno<->Elgg distributed friending functionality. Cross login functionality will come, hopefully, when I have time (although if you’re in a hurry you could always provide an incentive!).