Google’s short history as a public company passed another milestone overnight with its shares trading for more than US$500 each. Not bad for stock issued at $85 in the IPO two years ago.

Google is now valued by the market at more than IBM, Apple, Orica or Intel – all far more established companies with greater sales, but of course the market gamble in tech stocks is all about the future.

To put it another way then, Google is valued at more than Yahoo, eBay and Amazon combined. At US$509.65, it’s on a price/earnings ratio of 65 and there’s still plenty of talk about upside. A Bloomberg report found only one analyst with a sell recommendation on it.

But not everyone is starry-eyed. Marketwatch.com tech writer John Shinal sees Google now as what Cisco Systems was in 2000. In March 2000, Cisco became the most valuable company in the world.

Cisco is still a very valuable company. Cisco and Microsoft are the only tech companies worth more than Google. But Cisco’s valuation is a fraction of that heady dot-com bubble peak.