Are There Bubbles In The Cloud?

I recently wrote an article on Seeking Alpha on the valuations of disruptive and high growth companies in cloud software and social networking such as FireEye (FEYE), Splunk (SPLLK), Twitter (TWTR) and Workday (WDAY) and whether these valuations suggest we might be in a mini tech bubble in these sub categories within the overall technology sector.  I also was recently interviewed on Bloomberg TV on this topic. Valuations of these and other cloud/social companies are very high (i.e. ranging from 30x-60x trailing EV/Sales) when one looks at the post Tech Bubble era, but they are nowhere near the valuations we saw of high flying disruptive companies in 2000 (e.g. Juniper Networks peaked at around 400x trailing EV/Sales in 2000).  While these current valuations are not even close to the levels we saw in 2000, they are generally higher than the post bubble range of 20x-40x EV/trailing sales for best in class software/Internet companies Salesroce.com, VMware and Goggle when they were at similar annualized revenue levels.  A look back at the respective sales growth rates and valuations of these best in class enterprise software and Internet companies, suggests the current class of disruptive enterprise software, Internet and social networking companies may still offer positive stock returns from current levels over the next 3-5 years, but that these new class of companies will likely need to grow at the same historical rate (or better) as the prior best in class group.  Even if this new class of companies can replicate the growth rates of CRM, VMW and GOOG when they were at the same revenue size, large stock corrections of 25%+ are likely and an overall negative return over the next 3-5 years cannot be ruled out (e.g. if one purchased VMware at its peak valuation in October 2007 of ~40x trailing EV/Sales, you would still be underwater on the stock).