Really. According to United States Patent Application 20130297301, this is one of Google's latest ideas to make your smartphone even smaller and even more closely connected to you than you had ever imagined.
If you read through the document far enough, you'll note that the tattoo isn't permanent, but rather an electronic tattoo on a flexible substrate on your throat. This device would then communicate remotely with your smartphone in a few revolutionary ways. The tattoo is, for instance, a nearly perfect microphone. It filters out almost all extraneous noise because it relies on vibrations in your throat (and adjacent vocal chords) to encode sound, making it incredibly useful in noisy, crowded situations like concerts, subway trains or almost anywhere outdoors. Google also envisions some less intuitive applications, such as including a user-interface and display on your throat, and applying these tattoos to animals and pets.
They also mention that the tattoo could function as a lie detector, determining the behavior of the user by measuring the galvanic skin response. Would you wear your phone tattooed on your neck? If so, how much would you want it to tell others about you?