WWW::OpenSearch has been under "development" since May. Not much has happened since the 0.06_02 release in June, so i was glad to finally get the go-ahead from miyagawa to release a new stable version.
My motivation for all of this work has been the need to have a perl client for the Lucene Web Service. We (Adam and I) constructed the web service in such a way that searches on the indices would return an OpenSearch feed. The rest of the API is based on the Atom Publishing Protocol. This makes it super easy to wrap XML::Atom::Client and WWW::OpenSearch to make our own webservice client mashup.
The client is only in the svn repository for now, but we hope to release it as well as a Catalyst model to tie the two together in the new feature.