So anyway here is an extract from the Guardian's layman's explanation...

What is Operation Twist?

When you play the card game pontoon, you have the option to "stick" – keep the hand you are holding – or "twist" – draw another card. Until a few months ago, the Federal Reserve believed it had a strong hand in the battle to kickstart the US economy and was prepared to stick. But recent events have shown the economy struggling and unemployment staying high. Now it must twist.
What happens in practice?

Over the last two years of quantitative easing, the Fed has acquired a hand that includes $1.65 trillion of federal bonds – in other words, loans to the US government. Some of these bonds will mature in one or two years, some not for much longer – up to 30 years. If the Fed trades in some of its shorter-dated bonds for more of the longer-dated alternatives, demand for the longer-dated variety will exceed supply. This in turn will drive up the price of those bonds, which depresses the "yield" – the effective rate of return the holder of the bond gets on their investment. The yield determines the interest rate. Lower long-term interest rates will lead to lower 25-year mortgage rates, car loans and other bank lending rates.


Read more: here

If this is too boring for you, there is something more interesting...

The Fed yesterday reminded me of a manager who has nothing useful to do, so sets about re-arranging his files ... trying to look busy.

a) The cost of borrowing is not what has been holding up the recovery, so any meddling in that department was unnecessary - and as it turned out, counter-productive

b) after throwing billions in good money after bad (saving the zombie banks), the Fed has now made it harder for the banks to make money by 'flattening' out the yield curve... the banks will simply try to make up the difference by raising rates and by layering on charges - thus hurting both business and consumers.

Too late, economy is already 'bust'.