Efforts to locate an entrance to the Sansha's base systems have been underway since the attacks began. Recently, a lone pilot managed to get a probe through one of the Sansha wormholes. The probe relayed a single image of the Sansha forces and the wormhole's target system before being obliterated.
http://www.massively.com/2010/06/29/eves-sansha-live-event-takes-an-interesting-turn/