Updated from 12:13 p.m.

Google's

unorthodox initial public offering unveiled another surprise Friday: The risk posed by

Playboy

magazine.

In an amended IPO prospectus filed Friday morning -- the same day that

bidding opened in Google's long-awaited auction of its shares -- Google warned that a newly published

Playboy

interview with the company's two founders could have

expensive consequences.

Specifically, Google warns that if a court finds that the September

Playboy

interview constitutes a securities law violation, "we could be required to repurchase the shares sold to purchasers in this offering at the original purchase price for a period of one year following the date of the violation."

Google says it doesn't believe that the interview with co-founders Larry Page and Sergey Brin violates securities laws. The company, which reprinted the interview in an appendix to the latest filing, says, "We would contest vigorously any claim that a violation of the Securities Act occurred."

At issue is the so-called quiet period surrounding IPOs, in which companies are expected to limit extraordinary communications to the public to material that is in their IPO filings.

In the past, violating "quiet period" rules has forced companies to delay their IPOs. Earlier this year, for example, customer relationship management firm

salesforce.com

(CRM) - Get Report

delayed its IPO after the company's talkative CEO, Marc Benioff, spoke of the company's prospects in an article in

The New York Times

.

Back in 1999, now-defunct-grocer

Webvan

delayed its IPO after

TheStreet.com

reported that

the company was disclosing important details about its business to institutional investors that it wasn't including in public filings.

On Friday, citing a person familiar with the matter,

The Wall Street Journal

reported that regulators are expected to let the Google offering proceed apace.

In its disclosure about the interview -- which Google says took place in April, before the company first filed to go public -- the company advises investors to place the interview and the accompanying article in a larger context. "The article presented certain statements about our company in isolation and did not disclose many of the related risks and uncertainties described in this prospectus," says Google. "As a result, the article should not be considered in isolation and you should make your investment decision only after reading this entire prospectus carefully."

In fact, the search-engine company corrects or updates some assertions in the story. For example, contrary to Page's indication that Google had "about 1,000" employees, the company says it has 2,292. And though

Playboy

says that more than 65 million people uses Google each day, the company says it believes that 65 million is a third-party estimate of how many Americans visit the site each month.

As for information about Google's business that might be of interest to potential investors, there are a few nuggets in the interview that weren't previously in the prospectus.

One part of the interview covers Google's presence in China -- a market that represents a potentially huge market for Google and other media companies, but which presents an equally large challenge given limitations on free speech.

Brin notes that other search engines have established local presences in China "and, as a price of doing so, offer severely restricted information." He adds, "We have no sales team in China."

Asked, "What would you do if you had to choose between compromising search results and being unavailable to millions of Chinese?" Brin responds, "There are difficult questions, difficult challenges," and doesn't offer a direct answer.

Elsewhere in the interview, Page speaks critically of the "portal" business model engaged in by

Yahoo!

(YHOO)

,

Time Warner's

(TWX)

AOL and

Microsoft's

(MSFT) - Get Report

MSN -- the strategy of creating a Web site with "sticky" content that keeps users on the site.

Saying that portals favor their own content over better content that may be elsewhere, Page says, "We want to get you out of Google and to the right place as fast as possible. It's a very different business model."

Page also says the controversy over privacy issues related to the company's Gmail free email product was a learning experience, and indicates the company mishandled the rollout. "We could have done a better job on the messaging," he says.

People who read the

Playboy

interview in Google's prospectus in place of buying the magazine will miss out, however, on one bit of information of interest to investors: a Playboy Party Joke about a dead stockbroker who gets to decide whether he wants to spend eternity in heaven or hell, based on short-term visit to each location.

After an enjoyable three-day visit to hell featuring women, gambling and liquor, the stockbroker picks hell -- only to encounter fire, torture and despair. When he asks the devil, "Why did you lie to me?" the devil responds, "Yesterday you were a prospect. Today you're a client."