What's the dope on Social Registers?

A drunken and distant friend recently boasted to another person at a party that he was listed on the Social Register up in Washington, D.C. His comment provoked a mixture of blank looks and feigned yawns.

Then as now, I really don’t know much about Social Registers. How many cities have them? Only larger ones? How does one get listed–what are the general criteria? What purpose do they serve, other than snob appeal?

Discuss.

Wikpedia.org is your friend. IMHO they appear to be self-delcared groups of snobs.

Our Fearless Leader has also held forth on this subject.

AKA a Mutual Admiration Society