An awesome new trick from Google. They always makes the best April Fools jokes! For more Google pranks and tricks, see:
Google hoaxes and practical jokes

Here's another guide on Facebook Cover photos:
Facebook Timeline Cover Photo Guide

Google has several other ester eggs and played a lot of practical jokes on their more “gullible” users.
See more of that here: www.vectorash.ro/google-hoaxes-practical-jokes/