“I CAN’T decide what I like poking more: you, or these bubbles,” says bubble-blowing Kim Kardashian, a reality-TV star, in a new application for Facebook (see right). Cameo Stars, the company responsible for this innovation, lets Facebookers send to their online friends clips of minor celebrities mouthing generic greetings. Besides enriching the world’s culture, the firm may also make a fortune. But gloomy types wonder if the profusion of highly valued internet start-ups with lighter-than-air business plans is evidence of a different kind of bubble.