This doesn't necessarily prove the crop circle was accurate though. Science may not be able to predict solar flares and sunspots ahead of time, but periods of solar activity such as the 11 year sunspot cycle can be predicted. We are currently in a period of increased solar activity that will be peaking around 2012. In other words, its easy to predict something that already has a good chance of occurring.
So it may not be smoking gun proof of the predictive power of crop circles, it's still interesting enough to make note of.