Their dual mandate was supposed to be low unemployment and stable prices.

Their "desired 2% inflation rate" is far from low and stable.

Info below credited to Mr Denninger's post located here.

"The Fed Mandate is for stable prices, not 2% inflation.  Need I remind everyone that a 2% inflation target, if met over a 45 year working life (age 20 - 65) results in a price increase of 144%?

Of course the actual performance of The Fed historically is closer to 3% inflation.  That's a 278% inflation over the same 45 years.

Put another way if you earned $1 in purchasing power at age 20 and saved that dollar, you have about 35 cents left at age 65.

And this is Bernanke's intent."