With valuations of tech companies reaching the multi-billion-dollar stratosphere, a question that's consistently been on market watchers' minds this year is whether it's 2000 all over again. Is this the next dot-com bust? Those who say no argue that the value of today's tech companies is here to stay.

Perhaps the best people to ask are those who actually run the companies. The Financial Times and The Economist released their quarterly survey of global business executives today. It's jam-packed with data from nearly every conceivable industry. But what caught our eye was what the 117 tech executives are saying. A majority of them--51 percent--admitted that they believe there's a bubble. In fact, tech executives were more likely than other executives to believe there's a bubble--only 38 percent of all business executives thought so.

Of course, because the survey participants were non-randomly selected by journalists, it should be taken with a grain of salt. And this statistic may be fueled in part by the struggling global economy rather than the state of today's tech companies. 

As in the dot-com bust, today's rapidly growing tech companies--many of them social networking sites--provide a service users want. It's generating revenue from those online services that may be the problem.