OWL (or other language) ontology for unit conversions

Hi all,

I notice that earlier this year there was extensive discussion about 
possible extensions to OWL for describing units and unit 
conversions[1].  I haven't been able to find other discussion since 
then and I've started a project where it would be nice (and maybe 
required) to describe the units in a standard way.  Does an OWL 
ontology for this exist?  If it doesn't exist in OWL, does anyone know 
of such a thing defined in other ontology languages?

Finally, what happened regarding the recommendations made in [1]?

Thanks,

Nick Knouf
Lab Manager, Kanwisher Lab, MIT

[1] 
http://lists.w3.org/Archives/Public/www-rdf-interest/2003Jul/0104.html