Before this week, it was safe to say that expectations were extremely high for Google (GOOG) heading into this afternoon’s third quarter earnings announcement. But now that fellow Internet bellwethers Yahoo (YHOO) and eBay (EBAY) have both reported third quarter profits that topped forecasts, Wall Street will expect nothing less than perfection from Google.

Google’s stock has soared 38 percent this year and is up 15 percent since the company missed second-quarter earnings forecasts in July. But investors have already forgiven Google for this transgression. In fact, many on Wall Street believe that the world’s top search engine company will beat estimates…and by a wide margin to boot.

Remember that whole “whisper number” phenomenon in the late 1990s? These were unofficial earnings estimates that Internet stocks were expected to beat. And more often than not, the “whispers” were higher than the official consensus forecasts of Wall Street analysts.

Well, people are chattering about Google. According to Thomson First Call, analysts are predicting that Google will report a profit of $3.78 a share. But if Google reported merely $3.78, it’s highly likely that investors will be disappointed. One site that tracks whisper numbers, whispernumber.com (free subscription required), is reporting that the whisper number for Google is actually $3.82 a share. And another site, earningswhispers.com, has set the bar even higher for Google; it is reporting a whisper number of $3.95 a share.

Now let’s be honest: This is all really silly. The fact that people paid attention to whisper numbers in the late 1990s was one of the worst examples of bubble-era excess. And it’s foolish for long-term investors to take these projections seriously. If Google were to report profits that are simply in line with forecasts, it’s not a sign that Google is losing its mojo.

After all, if Google’s earnings come in at $3.78 a share, that would represent a 44 percent increase over the same period last year. That’s obviously extremely impressive. Yahoo’s profits declined in the third quarter.

But Google, last quarter notwithstanding, has typically surpassed Wall Street’s estimates by a wide margin. So it’s worth paying attention to the whisper numbers for a clue about how the stock might react immediately after the results are announced this afternoon.

If Yahoo, which has, to put it mildly, struggled in its attempts to stay competitive with Google, can beat Wall Street’s targets, it seems safe to assume that Google will do so as well.

“A majority of our clients’ search dollars go to Google. It’s not game over in search but they certainly have a big lead,” said Joseph Davis, president and CEO of Coremetrics, a Web analytics firm that works with more than 1100 advertisers. “And even if companies are decreasing their overall ad spending, that’s offset by the significant shift online. We have no client that I can think of that is cutting its online ad spending.”

So it’s no secret that Google dominated search in the third quarter. To that end, Web research firm comScore reported Thursday that Google’s search market share lead over Yahoo and others grew in September.

Google finished the month with 57 percent of the search market in the U.S., up from 56.5 percent in August. Yahoo’s market share also rose, but by a slightly lower amount than Google’s. Yahoo had 23.7 percent of the search market in September, up from 23.3 percent in August.

Therefore, it will be more important for investors to focus on what’s next for Google. My colleague Adam Lashinsky at FORTUNE recently sat down with Google’s power trio — chairman and CEO Eric Schmidt and co-founders Larry Page and Sergey Brin — and he reports that Google’s top brass is as confident (and arrogant) as ever.

But one big question that’s likely to pop up during the conference call is what will happen with Google and its online video subsidiary YouTube in the wake of reports that several media conglomerates and Internet firms have reached an agreement on protecting copyrights online.

The Wall Street Journal reported Thursday morning that Viacom (VIAB), CBS (CBS), Walt Disney (DIS), News Corp. ’s (NWS) Fox and GE’s (GE) NBC Universal unit, in conjunction with Microsoft (MSFT), online video company Dailymotion and News Corp.’s MySpace social networking unit, will announce guidelines for blocking and eliminating pirated content that has been uploaded by users. Google is not part of this agreement, however, according to the report.

UPDATE: Later Thursday, these media and tech companies, as well as online video startup Veoh, unveiled a Web site called ugcprinciples.com that detailed their proposed guidelines for posting copyrighted content. The site has the following tag line: Encourage Creativity. Respect Intellectual Property.

Viacom filed a $1 billion copyright infringement lawsuit against Google and YouTube in March and several smaller media firms have since filed suits against Google and YouTube as well.

Google and YouTube announced on Monday that they were rolling out automated technology to filter and block the illegal posting of copyrighted clips. But one analyst suggested that the agreement between media companies and YouTube rivals could force Google to also agree to these same standards.

“Now we see why Google was in a rush to announce that it would soon employ a proprietary solution to inhibit the posting of copyrighted files — because once an industry initiative is formed, Google will be forced to accept the common model rather than use its own solution as a competitive differentiator. The pressure on Google to go along with this cooperative initiative will be intense, as the fate of existing lawsuits will likely hinge on Google’s acceptance of the common solution,” wrote James McQuivey, a digital media analyst with Forrester Research, in an e-mail.

So once Wall Street stops whispering about Google’s third-quarter results and how strong they were, investors should settle down and take the time to listen to what Google has to say about this new challenge to its online video advertising strategy.