Once I hear a group of social "scientists" employing the term, it generally means that are looking for reasons to favor some groups (almost always Democratic constituents), while excluding others...
We all have our own idea of social justice. My form of social justice is a little different. I would have people keeping the money they earn without the force of a gun to their head with orders to turn larger and larger amounts of it over to the government as they become more successful. I would also call it socially just to have people pay for their own health care without mandating others by force to pay for them.
Is the current form of "social justice" with its emphasis on government force for some special interest groups but not for others really justice?
The answer to the rhetorical question is no.
Update: Art taught in schools, and the tie-in with social justice, is discussed here.