Cool project. Much like Ruby, Python seems easy to match to JSON.
Also, check out JsonML : http://jsonml.org/ . The focus lies more on the client side templating (where it's all JS anyway), but it has additional goodies like XML-to-JsonML XSLT transformation.
Also, check out JsonML : http://jsonml.org/ . The focus lies more on the client side templating (where it's all JS anyway), but it has additional goodies like XML-to-JsonML XSLT transformation.