Following the worst recession in decades, bullishness appears to have returned to Wall Street and in the corridors of corporate America as a new wave a high-profile acquisitions and possible IPOs by prominent tech companies brings back memories of the dot-com boom.

The only question is whether all this exuberance is truly rational.

On the heels of Microsoft's $8.5-billion acquisition of Skype last week, LinkedIn kicked off what some think could become a stampede of tech IPOs by going public Thursday.

Given the early returns—LinkedIn shares more than doubled in their first day of trading Thursday—the pressure on other private tech firms to do the IPO thing, and soon, has ratcheted up.

This is particularly true for companies operating in the somewhat nebulous tech segment known as "social networking." LinkedIn is the first tech company with roots in the mid-2000s Web 2.0 boom to have gone public and now the Street is hungry for more.

The crown jewel in all of this is, of course, Facebook. The premier social networking site has been around long enough now to have convinced even the biggest skeptics that it's for real. Facebook has emerged as a legitimate rival to established tech giants like Google (even if Mark Zuckerberg's company can still look amateurish at times).

There are other tech companies we'd like to see go public. Along with some that really shouldn't. Click ahead to find out which IPOs really need to happen ... and which ones most assuredly don't.