The profile of the IPO market is currently at its highest level in a decade thanks to a wave of fast-growing second-generation Internet IPOs and pending offerings from some even more hotly anticipated companies. US IPOs like LinkedIn, Pandora and HomeAway and international firms like Renren, Youku.com and Yandex are commanding billion-dollar valuations. There are rumors of $20 billion+ valuations for Groupon and Zynga and a possible $100 billion market cap for Facebook when they follow suit in entering the public markets in the coming months.

Despite the intense interest in these second-generation Internet companies, there is significant and serious debate about what they are truly worth. They have achieved impressive growth to date and address large opportunities, but they still have a great deal to prove.

The last time general interest in IPOs was as widespread as it is now was in the dot-com bubble just over ten years ago. It is tempting at first glance to compare the current environment to the bubble. However, there are significant differences between the two timeframes.