[ttronicm]

Why not just bring up the supporting evidence that was required for you to join Mensa? With 2 out of every 100 people qualifying for membership, you could swing a dead cat in a crowd and be pretty likely to hit someone who is qualified. OTOH, how many of them would choose to join an organization that celebrates exclusion and superiority? Being a member says something about your disposition and personality.

Among the most important adaptive techniques for exceptionally smart people in a crowd of averageness is inclusiveness. With the current emphasis on team building during the hiring process, listing Mensa risks making you look like an exclusive arrogant ass unless you know the hiring manager is also a member. If that's the case, I would specifically mention that you included your membership in Mensa on your resume for that very reason.