An interesting sidebar, part of Hillary Rosen's argument is that the Federal Government does NOT consider child rearing, if they're your OWN children, as being 'work' so therefore her claim is legally accurate. Whether you agree with that position or not, there is an interesting bit of karma at work here.
Until a few years ago the federal government never needed to classify child rearing as work or not. Irrespective of whether anyone thought that it was or not didn't matter since it was never a factor in anything other then how people felt about the different roles people played in a family.
But when they decided that we had to do something about all those people on welfare suddenly this was going to matter.
What happened was that in 1994, a large number of Republicans were swept into office as part of Newt Gingrich's 'Contract with America' campaign and one of their top priorities was to 'solve the welfare program' and so they came up with this 'work for welfare' idea where after two years you had to go out and get a job or you'd lose all of your benefits.
However that required a legal definition of what is and what is not 'work', and since one of the groups that this was targeted at, single welfare mothers (and I guess single welfare fathers as well), if you allowed child rearing to be considered 'work' then they could stay at home and continue to collect their welfare checks as long as they kept having kids.
So thus was born the Personal Responsibility and Work Opportunity Reconciliation Act of 1996 (PRWORA), a law which officially declared that raising of you own children could NOT be considered as 'work' which was critical for this law to have the effect that it was intended to have, that is 'force' welfare recipients to go out and get jobs.
Anyway, that's the law that Ms. Rosen has sited as being the basis for her assertion that Ann Romney has 'never worked a day in her life', and we can all thank Newt Gingrich for Ms. Rosen being able to say that with a straight face, even if it probably was a bit naive to think that she wouldn't get any flack over saying it quite the way she did.
So if Ann or Mitt Romney wants to object to the idea that child rearing is NOT 'work' they need to take that up their Republican colleagues, and Newt Gingrich in particular.

OCU