What is the meaning of the Hindu greeting "Namaste"? (105)

Hindus and New Agers often greet each other with a respectful gesture of folded hands and a slight bow as they utter the word “Namaste.” Many yoga classes open with this exchanged statement. Is this just an ordinary greeting like “Hello” or is there a deeper, spiritual connotation? If so, what is it, and how should we respond?