My mother lives in a high-rise in downtown Philadelphia. We were talking on the phone last week when she suddenly stopped and said, in a wondering voice: “Look at that. It’s a dirigible,” accenting the second syllable: di-RIG-ible. (My mom is elderly.) I realized later it was the Conan blimp, a brilliant viral marketing gambit for the upcoming Conan O’Brien show on TBS. The blimp is fitted out with a number of whiz-bang bells and whistles, including the capability to auto-check in at Foursquare, if you go for that sort of thing. And I wondered: Where does an idea like this come from? The blimp itself was designed by Blue Sky, an Atlanta agency, with web design and social-media stuff by Breakfast, a New York firm with an appealing retro-futuristic sensibility. It shouldn’t be surprising, I guess, that the lightbulb moment for guys like these came when somebody sat up straight and blurted out: “A blimp!” Or maybe, in this case, “A dirigible!” And in a sense, the roots of the Conan blimp go back, way back, all the way back to May of 2010. (All right, maybe that’s not so far back, but things move so fast nowadays.) That’s when Breakfast rigged, for the New York design event MunNY, an iPad-controlled video blimp. It was 52 inches long, silver, and video-enabled (of course it was) and it circled the MunNY afterparty at a dizzying height of about eight feet, beaming a live feed back down to the skinny, well-dressed crowd below. What was it Springsteen said — “From small things, mama, big things one day come.”