This might be just a coincidence, as it seemed we had solved the question of the prior home page, which showed a Google "O" being beamed up. In terms of the new mystery, it's true that some searched for crop circles via Google Earth, but that's an ongoing use, not an "event, which is what Google's doodles are usually for.
Google added to the mystery with a tweet, which said:
51.327629, -0.5616088 http://twitpic.com/hsfgl
Those coordinates lead to, not crop circles, but when mapped in Google Earth, 51.327629, -0.5616088, which eagle-eyed sci-fi fans have identified as the center of the small town of Horsell in Surrey. This was the location where H.G. Wells set the first UFO landing in his novel "The War of the Worlds."
Coincidentally, next week will be the 143rd anniversary of H.G. Wells' birth. On the other hand, clicking on the Google doodle doesn't bring up H.G. Wells, but a query on crop circles.
Will we know something next week, about what the real reason behind Tuesday's doodle is? Will we ever know? Or will we keep going around in (crop) circles.
At any rate, watch a video that shows some crop circles embedded in Google Earth.