My left eye is open for at least some of the circles being "out-of-this-world" in the sense of not being made by the physical man.
Proving that something CAN be done by conventional means, does not nessecarily prove it was done that way. As Hiram says above, it still fails to prove why no one ever see who's making the ones that have no one claiming responsibility and proof of action.
Until it can be proven that all circles are man-made, I'll keep the interesting part in mind.