The runtime environment and parallel execution of the ab initio electronic structure package GAMESS is handled by the distributed data interface (DDI). In addition, DDI provides application developers with a virtual shared memory environment built around the model of a parallel global address space that is portable to all major hardware classes. DDI has proved to be a robust implementation and currently supports more than twelve different types of distributed data quantum chemistry application in GAMESS. A decade on and we are planning for the forthcoming era of petascale computing resources that pose new challenges for DDI. In this seminar, I will describe the implementation and use of DDI in GAMESS and work underway to enable DDI to support petascale quantum chemistry applications. This work is support by NSF grant "Enabling Petascale Applications in the Chemical Sciences" (Award 0749156).