Did the futures markets fail?

Atrios points out:

Well, the magic power of market predictions is not so magic.
The magic market was heavily predicting Senate control would remain with the Republicans. Oops.
And, hey, so was I. But the idea that there's something magical about market aggregated preferences seems to have infected the minds of too many people. They provide a cute distillation of conventional wisdom, but that's all..)

Is this really evidence that the market is unable to accurately aggregate information? If I toss a coin and it comes up heads, was my 50-50 prediction wrong? By the way, here are links to the IEM. [AF]