Google posted yet another quarter of eye-popping financial results yesterday as second-quarter profits more than quadrupled on higher-than-expected advertising sales. Meanwhile, Google's share of the global search market rose to 55% in April from 47% a year earlier, while Yahoo fell to 22% from 25%. The obvious questions are: how much better can things get for Google and how high can investor enthusiasm drive its shares, which touched $320 in after-hours trading before dropping to $280 amid concerns over slower sales growth. Google CEO Eric Schmidt appears to be trying to temper the bullish surrounding Google's prospects by suggesting to analysts that 15% sales growth isn't a given. A sign of the times could be the cautiousness of ThinkEquity analyst John Tinker, who achieved some notoriety when he slapped a $330 stock price target on Google several months ago. Tinker now suggests the "easy money" has been made and that institutional investors are no longer under-weight.