I just had a chance to look at the thanks-for-coming-to-google-io t-shirt that they hand out when you register and sure enough there was something interesting on the back. Let's take a look...
Here is the Morse code on the back:
.... - - .--. ---... -..-. -..-. --. --- --- .-.-.- --. .-.. -..-. .- ....- -.-. -.... ...-- ----.
Which converts to:
Which is basically the hex code for androids very own nifty shade of green. That short url goes to:
Now go download some android apps! Thanks for the fun, Google.