"Bubbles are empty vessels," says Scott Cutler, NYSE Euronext's executive vice president and head of listings, Americas, when asked in The Deal magazine's video roundup if we're seeing a bubble in social media. Facebook Inc., LinkedIn Corp. and Zynga Inc. have significant revenues, revenue growth, operations around the world and "most importantly have executed through the financial crisis, and that's different from the last bubble," argues Cutler. Foundry Group co-founder Jason Mendelson concurs. "As an investor in Zynga, I can tell you there are meaningful revenues," he says. Furthermore, LinkedIn Corp.'s successful IPO on the NYSE indicates investors are "thirsty" for social media, says GSV Capital Corp. co-founder Michael Moe. One note of caution comes from Theresia Gouw Ranzetta: "There is, in my opinion, a bubble in the earlier stages, where companies that don't even have products yet are raising tens of millions of dollars," says Ranzetta, a partner at Accel Partners, which backs Etsy Inc., Facebook and Glam Media Inc. For more on the topic, watch "Mendelson: Meaningful revenues in social media" and "Ranzetta spies early-stage bubble." - Mary Kathleen Flynn