Here is the proposal from OSCOM
http://www.oscom.org/events/oscom4/proposals/skins.html
Slides from the presnetation
http://www.oscom.org/midcom-serveattachmentguid-f37d6742f42270964a9fa628d43e45aa/oscom4.naming.conventions.pdf
An example of how it might be used to template Midgard
http://bergie.iki.fi/blog/standardized_css_layouts_with_midgard.html
I have chatted with the author of the proposal and he is interested in working with OpenACS on a cross-CMS standard.
A good place to get involved is the OSCOM Mailing List http://oscom.org/cgi-bin/mailman/listinfo/general