The debate is on, over whether we've entered Tech Bubble -- or Dot-Com, if you will --2.0.

Perhaps. But even if so, there are clear differences this time over what happened last time.

It's true that mounting facts support the argument that we are experiencing Tech Bubble 2.0, primarily because of what seems to be overzealous enthusiasm for Internet company stock IPOs on Wall Street in recent months.

Zillow, the home price Web site, is evidence of that argument. The company's stock went public in July in an IPO at $20 a share, but that price had more than doubled to $44 a share by the next day.

Zillow provides information about homes, real estate listings and mortgages, something that might not carry so much weight in a weak housing market if not for the company's dot-com modifier. Zillow has yet to turn a profit, but investors apparently like the company's growth potential simply because of its strong consumer Web presence.

Heard that before -- companies not making money finding big IPO success because they have a dot-com association?

Of course, but it's not the Dot-Com Bubble at the turn of the century I'm talking about. It's happened just recently, time and time again. There was the IPO of earlier this year of LinkedIn, a site for professional networking. That company's IPO doubled the price target at launch with so much investor appetite.

Then there was the IPO of Pandora, an Internet radio station, that doubled at launch before quickly settling back.

Among almost 90 IPOs in 2011, more than one-third have been from Internet or technology companies with more than 30 more expected by the end of the year, a number that will rank as the most since 2000, the peak of Dot-Com Bubble: Part One. Among the IPOs set to reach the market soon include Groupon and LivingSocial, two Web-based social daily coupon networks in fast-growth mode.

But many signal the apparent appetite for Groupon and LivingSocial, both expected to raise roughly $1 billion through IPOs, as example No. 1 that we've entered Dot-Com Bubble: Part Two. The companies are highly susceptible to competition, goes the argument, and unlikely able to support such lofty valuation as what they are attempting through impending IPOs.

There's clearly an Internet bubble, said David Bonderman, the founder of TPG capital, in an interview with CNBC.com in May.

Another tech analyst and investor agrees.

It's easy to say there is an Internet bubble, largely because there is, said Jonathan Nelson, the founder and chief executive at Providence Equity Partners.

But others are not so sure. They say Internet usage has grown substantially since the Dot-Com Bubble. Statistics show, in fact, that eight times more people use the Web today than in 2000. The Internet has also grown in capability, delivering content and services far beyond the original retail sales application that was so big before, fueling the growth of companies like Amazon and Ebay.

Translation: Making lots money on the Web is now a real possibility. It's not just a wing-and-a-prayer dream.

I don't see a bubble, venture capitalist Marc Andreessen, a founder of Netscape, told The Associated Press in March. I think people are confusing success with a bubble. Maybe stuff is just working.

The co-founder of LinkedIn agrees.

I certainly don't have such skepticism, said Reid Hoffman, in an interview with the Boston Herald. On the bubble side, I think that everyone is really into these companies because there's clear potential.

Potential is the key. Most of the tech and Internet companies finding roaring success on Wall Street with IPOs this year have yet to turn a profit. But they do have more to build upon than only the dot-com modifier that fueled IPO successes the first time around. Most of the companies today have large customer bases, strong revenue and models that show they can become profitable.

Before, it was anything goes. A company did not need a business plan, customers, or much anything else. Wall Street sent everything that had a dot-com attachment to its name at IPO launch hard to the north, into green numbers.

And that seems to be the biggest difference this time, that not just anything is going. Just companies with a proven ability to grow sales and draw up a respectable business plan are a hit in trading at IPO launch.

So even if we have entered the Tech Bubble 2.0 era, investors with a robust appetite for tech and Internet company IPOs can at least argue they are getting more for their money now than investors got the first go-round.

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