Several commenters on the germophobia thread mentioned that they are rarely in a position where a handshake is expected, or that it is not part of their culture - so I thought it would be interesting to get an idea of how common this greeting is, and in what contexts.
I live in the Southern US, and shaking hands is the expected standard greeting on being introduced in most social and all professional settings.
Professionally - in every line of work this is expected upon meeting employers/co-workers, whether in an office, a shop or on an industrial/construction site. Not between retail workers and customers, but definitely in any sort of b2b sales, car sales, professional clients, etc. Also when meeting a new doctor (though not nurses/front desk). After first meeting, it is not expected unless you have not seen each other for a while.
Socially - receiving lines for weddings are very common though not universal. In any all-male or mixed-gender social group, a handshake would be the expected greeting on introduction. Not necessarily in a all-female, purely social group.
For example, if I were out shopping with a girlfriend and we ran into a female acquaintance, we would not expect to shake hands on being introduced. However, if I were meeting other parents at the school Parent Night, or welcoming a visitor at church, handshakes automatically go with exchanging names.
What's it like where you live?