FYI, I got an ARC2 [0] based SPARQL Endpoint for SMW up running, implemented in a SpecialPage and connected to an ARC2 triplestore [1].

Try it out: http://smwsandbox.rilspace.org/wiki/Special:SPARQLEndpoint
Blog post: http://saml.rilspace.org/arc2-based-sparql-endpoint-for-semantic-mediawiki-up-running
Code: http://code.google.com/p/smw-rdf-connector/source/browse/#svn/trunk%3Fstate%3Dclosed

It is still in a very experimental stage, and a lot of refactoring remains (so beware of ugly code :-o). Also it is not at all connected to the "equivalent URI handling" that was described in the project description [2] is not
Feedback and hints are always welcome!

Samuel

[0] http://arc.semsol.org/
[1] http://saml.rilspace.org/working-arc2-rdf-store-connector-committed
[2] http://www.mediawiki.org/wiki/User:SHL/GSoC2010
-- 
Samuel Lampa
---------------------------------------
Biotech Student @ Uppsala University
   GSoC Student @ Semantic MediaWiki
---------------------------------------
   Blog: http://saml.rilspace.org
Twitter: http://twitter.com/samuellampa
---------------------------------------