A derogatory expression coined to describe the educated left-wing middle class. The implication is that members of the class are prepared to loudly moralize about left-leaning social ideals (i.e. chatter) but are not prepared to sacrifice their own comfort and wealth to attain those ideals.
The term is used by right-wing politicians, usually in response to intelligent criticism of their actions or policies. There is considerable irony in the fact that users of this phrase are typically far richer and less willing to help the underprivileged than those they are attacking.