Go to your iPhone or Android phone and search for the word [tilt] using Google. The search results displayed will all results at a slight tilt to the right. Our understanding from Google is that this is an April Fools joke that’s still running.
Here is a picture on the iPhone (it does the same on Android):
This doesn’t seem to work on the iPad, however. Searching for “askew” will also trigger it, Matt Templon reported to us.
Update: The “tilt” search also works on Google.com in desktop browsers, too.