To get started, pick up Microsoft's Tag Reader app for your mobile phone (find it at gettag.mobi). Then, watch this video. At the end you'll see a hidden orb, which you can scan with Tag Reader. If you'd rather not watch the video (again), you can just scan the image to the right. Once scanned, you can register for a contest account, which will provide you with text message clues about the locations of the remaining "orbs." Find them, scan them and you're in.
Orbs for demos, agent. Orbs for demos. Unless you don't have a texting plan, of course.