Egon Willighangen from the Wageningen University and Research Center has recently created a mashup for tagging molecules with connotea. You can read about this at this blog post, but essentially he is creating rdf output for molecules pages available from the open molecule site. If you bookmark these pages in Connotea the tags you use will be pulled out of connotea by the open molecule page and displayed on the page.
The format he us using seems to have settled down to the following form:
http://rdf.openmolecules.net/?info:inchi/InChI=1/CH4/h1H