Subhash Khot's Unique Games Conjecture is one of active research areas in complexity theory.What evidence do we have for it? What evidence do we have against it?
What evidence do we have for (and against) Unique Games Conjecture?
cc.complexity theory;unique games conjecture
Khot gave a UGC survey talk at CCC 2010. The write-up is here. The final segment (bottom of page 30) has his opinions on this question.