There was an article about these in the Wall Street Journal a while back. All the airlines have them, some more formal than others.

However, there's an upper limit to how far an airline can go. Commercial air travel, even in the best international F, is still commercial air travel. The uber-elite have private planes, corporate planes, fractional ownership and executive charters. Only very long trans-oceanic routes are beyond the range of most of these, forcing their users to slum with the masses. No commercial airline is going to get a significant share of those folks by giving them fancy lounges, airport greeters and the chairman's private phone number.

(Noticed after posting: ScottC's post just above was posted as I was writing this.)