Development on the Open Access Media Importer continued, and the contracts have been signed. Two blogposts detail the progress: the module for crawling PubMed Central's Open Access Subset is now functional and can identify supplementary materials from this set - or articles matching specific search terms - that are licensed compatibly with Wikimedia Commons.
The process works much like apt-get: for instance, oa-cache list-articles pubmed | grep Malaria | grep 'creativecommons.org/licenses/by/'
finds all Malaria-related papers licensed under CC BY. A session proposal on the Open Access Media Importer has been submitted for Wikimania.