Wireless Sensor Networks (WSNs) are used in many application areas including health, agriculture and gaming. New advances in sensor technology make it pertinent to consider sharing a deployed WSN infrastructure by multiple applications, including applications which are designed after the WSN deployment. For my PhD research I propose a novel WSN virtualization framework that allows multiple users to run their application tasks over underlying WSN resources in a transparent way. This paper presents the overview of the proposed WSN virtualization framework, related work, current status and future work.