A Gallup survey on dining suggests that it's the middle class which is doing the most to cut back on its discretionary expenditures.
Note that the frequency of dining out is essentially unchanged among American households making more than $75,000 per year, as well as those making less than $20,000 per year. Americans in the middle income brackets, however, appear to be dining out 15-20 percent less frequently.
Caveats: the sample size on this survey is relatively small (about 1,000 persons) and restaurant meals are obviously just category from among a large universe of consumer expenditures. Still, if one of the goals of the stimulus is to craft tax policy so as to entice consumption, it is important to know just who needs to be stimulated.