Ed Yardeni has published a very important chart showing the decline in the difference between long-term rates and short-term rates. Some of this may be due to Operation Twist, but it is also likely the result of the dramatic slowdown that has occurred recently in money supply (M2) growth.
The tightening of the yields means it becomes less profitable for banks to make loans, since banks tend to borrow short-term and lend long-term. The boom-bust business cycle is all about expansion and contraction of loans and money. Thus, the decline in the yield curve difference is another sign that Bernanke has the economy in crash mode once again. Bernanke is very erratic when it comes to money supply, so he could switch any day to rapid money pumping once again, but right now the plane is heading toward land with its nose pointing down.