By no means a complete CouchDB client, but what little is here works... Just experimenting with Groovy for simple RESTful JSON operations.
% wget http://repository.codehaus.org/org/codehaus/groovy/modules/http-builder/http-builder/0.5.0-RC1/http-builder-0.5.0-RC1-all.tar.gz
% tar -zxf http-builder-0.5.0-RC1-all.tar.gz
% git clone git://github.com/dougm/gcouchrest.git
% cd gcouchrest/examples
% ./grelax gcouchinfo.groovy
Welcome, CouchDB version: 0.9.0
Databases...
...
Same as Groovy and http-builder: http://www.apache.org/licenses/LICENSE-2.0