As a previous column noted, Google represents the culmination of the first Web search engine era. Its rise was due in part to a reaction against the portals and their increasingly baroque attempts to shoe-horn links to huge chunks of the Net into a single Web page. Google is simultaneously the ultimate portal and an anti-portal, with a studiedly minimalist home page (even if the logo varies).

Google has entered the language, the souls and the bookmarks of the world - probably most regular users of the Internet have made Google their browser's start page. Already an essential part of our Zeitgeist, the question is: What new Google will emerge in the wake of its IPO later this year?

Even before the IPO was officially announced, its prospect had been the subject of excited discussions. If Google's flotation succeeds in raising a couple of billion dollars, as the company hopes, this will be taken as a clear signal that the dotcom times are here again - to say nothing of irrational exuberance. Other IPOs are likely to follow in short order, and shares in the established Net companies are also likely to benefit. At the very least, then, Google will be become the undisputed bellwether of the next phase of online business - Netscape Communications 2.0.

But Google is attempting much more than a minor upgrade to the New Economy. For a start, the IPO will employ a Dutch auction. Moreover, as its IPO registration statement makes clear in the extraordinary "Letter from the founders" - subtitled "An owner's manual" for shareholders - once it has gone public, Google aims to be very different from most companies worth $20 billion, its likely nominal valuation. Two sections are headed "Don't be evil" and "Making the world a better place": Google the do-gooder.

Whether or not Google manages to pull off this high altruism in the face of base economics - and some already have their doubts about the company (while others doubt the doubters) - a separate issue is just what it plans to do with the proceeds of its IPO. After all, Google's management have been at pains to emphasise that the company does not need the money, since it has been profitable for some years.

One hint is provided by the registration statement, in which the company describes itself as "a global technology leader focused on improving the ways people connect with information." That is, not simply a search engine. This is certainly consonant with what is known about its proposed Gmail service, which turns an individual's online correspondence into a fully searchable set of Web pages, complete with sponsored links.

This re-purposing of the basic Google technology has moved some to view it as the first step in the evolution of Google into something much grander: a new kind of computing platform - GoogleOS - which can run applications like search or email across the Internet on an unprecedented scale. A technical paper describing what is called the Google File System - "a scalable distributed file system for large distributed data-intensive applications" - certainly supports this view.

What is significant about this idea is not so much that the underlying software will be GNU/Linux, but that it will make that fact as irrelevant to most users as the details of TCP/IP are. Naturally, this would also provide an additional incentive for Microsoft to crush Google just as it destroyed Netscape - another company that dreamed of rising above the operating system - turning the search darling's future into the failed Net pioneer's past.

Glyn Moody welcomes your comments.