We work in the Heritage sector and some people want to have access to our data via OAI-PMH, and as we are currently just deploying Alfresco it makes sense to use Alfresco to serve up this content. In the words of the Open Archives, we would be a 'repository', that exposes our extended content model (dublin core + more) for other organisations to harvest, as well as to share with our other systems eventually.
From the Open Archives Site
"Data Providers are repositories that expose structured metadata via OAI-PMH. Service Providers then make OAI-PMH service requests to harvest that metadata. OAI-PMH is a set of six verbs or services that are invoked within HTTP."
thanks for your interest
Paul