Currently, most Google search properties that are currently in a time zone that is September 15th, such as Google UK, are sporting a special Google Doodle that links to a search result for crop circles. It seems likely this logo will appear in the US soon.
The logo shows a flying saucer above a series of crop circles that spell Google. Well, almost — the L has been abducted. That similar to the last Google flying saucer logo from ten days ago, where an O was taken.
Postscript: If you look at the coordinates Google tweeted, you will see some added information about the location. Specifically, “Woking … is the town in which the Martians first land in H. G. Wells’ science fiction novel The War of the Worlds.” HG Well has his 143rd birthday coming up this September 21st, so maybe the mystery will be solved on that day?