Michael Jackson. Santa Claus. Some poor shmo dressed up like the Ask Jeeves butler. As long as I can remember there's been somebody to ring the Nasdaq opening bell. On Wednesday, though, there was no body ringing the bell. There was PackBot, the skinniest robot you've ever seen and the creation of Burlington, Mass.-based iRobot ( IRBT), which has pulled off one of the most successful and celebrated IPOs of the year. Of course, PackBot wasn't designed for photo ops but for disposing of bombs and hazardous materials -- so using him as a symbol of an IPO opens the door to a lot of easy jokes. But they would be out of place now: In its first two days of trading, iRobot's shares shot up to $34.50, or 44% above their $24 offering price. In early Friday trading, the stock slipped nearly 3% to $33.55. Even so, the occasion itself deserves notice because it can mean only one of two things: the Nasdaq is so desperate to drum up new IPOs that it's resorting to desperate gimmicks, or iRobot, best known for a robotic vacuum cleaner named Roomba, actually belongs in the public markets. Early indications are that the latter case is right. That may surprise skeptics used to hearing that someday robots will be cheaply available to handle a lot of tasks we're too busy to get to ourselves. But with Roomba, iRobot is the first company to mass market a mobile robot to handle such a task: cleaning floors. And since the Roomba retails for about $300, it's been able to sell 1.5 million of them in three years. A similar product called Scooba, which will clean and dry floors, is due out next year. "I don't think this is just hype," says David Menlow, president of research firm IPO Financial Network. "It's a good piece of timing and it's profitable. That makes it palatable in the eyes of investors."