Are stay-at-home moms rich elitists?

That's what a recent Salon piece about Hilary Rosen's comments about Ann Romney asserted:

... at this point staying home full time with your children is not only a choice but pretty much a luxury of the elite

Compare to what was stated on Salon just a couple of years prior:

Despite the popular notion that most mothers who don’t work outside the home are mostly wealthy elites, stay-at-home moms actually tend to be less educated and poorer than the rest of mothers, as we learned from recent census numbers.

Add to it the British version:

Ministers have redoubled efforts to persuade mothers to take jobs in the face of evidence that a big majority of the poorest families are two-parent families in which only the father works.

I'd guess that it's not all that unlikely that Canada would be similar. Things may have changed a bit in the last couple of years although, given the talk of a "she-cession" I doubt that it'd be marked by an increase in the percentage of working women.

(Edit: I should note that when comparing family structures, being "poorer" than families in which both parents are employed outside the home may not be particularly handicapping. No need to fork out for expensive daycare, perhaps reduced needs for things like an additional vehicle, business clothing, etc. Add in lower cost and most likely healthier eating as well - fewer restaurant bills, more fresh food).