The always-on nature of the Web is making live marketing stunts more and more common. Gap had its GPS-equipped reindeer, and the Old Spice guy, of course, did his live responses. P&G is tapping into this vein with a campaign for Downy that has comedian Mike Birbiglia living in a window of Macy's flagship store in New York's Herald Square for a week. The people of the Internet can go to Facebook to watch him hang out in his little space and communicate with him live via Twitter and Facebook messages. It'll be interesting to see the buzz he generates. Birbiglia's stunt is reminiscent of Mark McIntyre's 25-day on-camera cancer fundraiser with Canadian underwear brand Stanfield's—the main difference being, Birbiglia presumably has two testicles, to McIntyre's one. One good sign for the Downy campaign: Mike wasn't in the window early this afternoon because he was off doing interviews.