Google Inc. (NASDAQ: GOOG) hit $600, the latest of a long series of hurdles that skeptics including yours truly didn't think was possible. It's only a matter of time before they move even higher.

The company continues to chug along even in volatile markets. The stock is up about 30% year to date, eclipsing rival Yahoo! Inc. (NASDAQ: YHOO), which gained 9% during the same period, and Microsoft Corp. (NASDAQ: MSFT), which is little changed.

Interestingly, the stock didn't stay at $600 for too long, hitting a psychological barrier. Last I checked, the shares traded at $596.65. I think investors will soon get over their unease and push the stock even higher.

The question is how high? What's the next hurdle for Google? Is it $700? $800? $1000? Henry Blodget recently upset the Internet establishment by arguing that Google could reach $2,000 over the next few decades. Why stop there?

Will Google's stock ever top Warren Buffett's Berkshire Hathaway Inc. (NYSE: BRK.A) which now trades at the princely sum of $120,800? I am not sure if this will ever happen but the possibility is certainly intriguing. The company reports earnings October 18.

No doubt the faithful are waiting on pins and needles until then.

Yesterday Google Inc. (NASDAQ: GOOG) hit an all time high -- up six-fold -- a bit under three years after its $85 IPO. The proximate cause of the latest rise is a deal with salesforce.com, Inc. (NYSE: CRM). The deal could create more opportunities for Google to connect with salesforce's 32,300 customers -- each of whom is a potential advertiser who has not previously tried running online marketing campaigns through Google's automated system

I've posted bullishly on Google for a while -- most recently on Memorial Day. That's when Steve Mandel, head of $8 billion hedge fund Lone Pine Capital, said he believes that Google's growth potential is not fully understood by investors because its core market of paid search is still in "its early innings."

Google is getting more expensive but I suspect not overvalued. I don't know Mandel's earnings forecasts for the company; however last week it traded at $497.91 a moderate PEG of 1.38 -- reflecting a P/E of 43.3 on 24 analysts' consensus 2008 earnings growth of 31.4% to $17.45. That PEG is higher now -- 1.49 reflecting a higher P/E of 46.5 on a slightly lower 24 analysts' consensus 2008 earnings growth of 31.21% to $17.43.

I think Google could hit $1,000 because of the growth potential in the company's 84 different businesses which do not yet generate revenues and revenues from future partnerships like the one with salesforce.

Do you think it's time to buy or sell Google?

Peter Cohan is President of Peter S. Cohan & Associates, a management consulting and venture capital firm. He also teaches management at Babson College and edits The Cohan Letter. He has no financial interest in the securities mentioned in this post.

In an interesting story - but not unexpected - a Google shareholder is trying to get the company to do away with the current stock voting structure that he says (and I agree with) gives too much voting control to the founders and CEO of Google, Inc. (Schmidt, Brin and Page, respectively).

Together, these three tentpoles to the Google empire have voting rights on over 68 percent of the company through their combined Class B shares. That's a lot on control for a company with a $100 billion market cap, eh? I have to agree with this shareholder in that there is way to much voting power tied up in too few hands - but releasing that power may make Google succumb to the evil shareholder forces that sometimes leap into action - hence Google's mantra of "do no evil".