Here's a synopsis of what I think is going on:
The dollar is at record lows and sinking further. The only way to raise the value is to create demand, but there is none (wink wink). Notwithstanding the fact that with the countless derivatives and odd angles to play the market, most every individual and institutional dollar is "all in" - some several-fold. This is already getting too complicated, so I'll get to the point. Smart, conservative investors buy low. Banks and countries around the globe would love to get in on the cheap dollar, but they're very concerned about where a bottom might be. So, Uncle Ben and JP Morgan took Bear Stearns to the top of the highest mountain and shot her in the head for everyone to hear. This ridiculous shot heard 'round the world has brought everyone out of the woodwork to feast... and sent up a very bright and distinct flare benchmarking value.
Treasury notes have begun to be eaten up. I suspect large foreign banks are the buyers, particularly where the dollar trades weakest and capitalism is welcome. Europe, Japan... And they all got tipped off by Uncle Ben before it went down so they could watch it go down - and buy, buy, buy as it unfolded.
But's that's just one man's opinion.