These numbers show great mobility, upward and downward, and it's why "class" as a political wedge issue hasn't typically held traction -- though the Obama administration is doing its best to change that dynamic.
No doubt, the recent recession -- and "stimulus"-induced extension of that recession -- and structural and technological changes that often occur in the job market mean that every so often, we will have some painful times. Taking a snapshot of "inequality" when emotions are exacerbated by a recession is only meant to distort reality for political gain. And every time capitalism is hijacked by technocrats and bureaucrats, it seems there is a cry from other technocrats and bureaucrats (and their fellow travelers) to institute more of the top-down control that stifles mobility.
You will notice that the Occupy Wall Street crowds -- and the progressives who support them -- focus on bringing the wealthy down to earth rather than lifting the 99 percent. They have a nearly religious belief that too much wealth is fundamentally immoral and unhealthy for society. The economic systems they cheer on would coerce downward mobility for the sake of equality but ignore prosperity for the people they claim to represent.
If progressive were interested in mitigating inequality, they would support the dynamism of free markets to allow the merit of ideas, products and services to win the day rather than stifle companies and pick winners in the name of imagined "progress." Yes, "too big to fail" means banks, but it also means union-backed bureaucracies, political parties, car companies and green energy -- and more.
If they were interested in spreading wealth, they would support lifting barriers that inhibit markets and make life difficult for entrepreneurs and businesses rather than spreading the destructive notion that life can only be "fair" if we rely on dependency and entitlement and tear down those who have more.