Google always has some fun with its I/O t-shirts and this year is no exception. There was a hidden message in the shirts, which appeared to have some sort of binary or Morse Code on the back. You can take a look at the shirt below and see if you can decipher it before continuing after the cut for the answer.
Putting the dots and dashes in line and considering the line breaks to be spaces, it turns out to indeed be Morse Code. After plugging it into a Morse Code translator you will find that the message is actually HTTP://GOO.GL/A4C639. An interesting note about the URL is that the “A4C639” is actually the HEX value for the Android green color.
Plugging in the URL in your browser, you will find that it forwards you to a page that invites you to Androidify yourself with the limited edition Google I/O 2011 t-shirt. Google sure knows how to have some fun. You should check out the 'Android Eats Apple' wallpaper that was displayed on the big screen during the first day's keynote.