Two projects claim to do this already: 

 * [https://sourceforge.net/project/showfiles.php?group_id=108268&package_id=116868&release_id=236821 Sesame-Jena Adapter] - A SAIL for Jena model. (i.e. access Jena through sesame api) - Last release May 8th - 2004.
 * [http://www.ecs.soton.ac.uk/~wf/jsm.htm Jena Sesame Model] - A wrapper for a Sesame Repository, conforming to Jena Model and Graph interfaces. - Last release: July 2005 - (Claims to) work with Jena 2.2 and Sesame 1.2

We need:
 * Something that works with Sesame 2
 * Sesame Repository -> Jena Model 
 * Jena Model -> Sesame repository
 * What about Jena Graph interface?