In all developed (and most developing) countries the public is now heavily dependent on software in nearly all walks of life - from email to e-banking and e-voting. Most agree that software applications have changed and largely improved the peoples' lives. Software's social sustainability is an important concern that needs an in-depth investigation. This paper is to understand what social sustainability is, how it is measured today, and how is social sustainability of a software system evaluated today. The authors present the initial results of a systematic literature review on these questions. Their findings so far highlight a large gap in work on software sustainability assessment.