To read some of the press coverage and analyst quotes, you would think that Google's recent stock plunge is due entirely to the company's refusal to give "guidance" (Translation: to tell analysts what to "estimate"). In fact, the plunge has nothing to do with the lack of guidance. It is the result of 1) slowing growth, and 2) investor expectations finally having exceeded reality (something that happens routinely, with or without guidance).
If Google were to give "guidance"--and nothing says it has to--the guidance would likely be intentionally low-balled, just like most companies' is. If it wasn't, Google would likely "miss its numbers" as often as it hit them, and thus be accused of being unable to forecast its results (and, in the process, screwing its investors). Analysts, therefore, would assume that the company's guidance was low-balled, and adjust their estimates accordingly (or they would just tell everyone to expect "upside"--which everyone duly would). So if the company merely hit its numbers, as it did in Q4, the stock would tank.
Google's recent communication gaffes are serious and need to be addressed immediately. If the company is committed to the no-guidance policy, then this should include "no commentary about financial performance between quarterly conference calls." The communication problems, however, are separate from the guidance issue.
I respect Google for not giving guidance, a practice that often reduces analysts to parrots with spreadsheets. Without guidance, analysts have to actually develop estimates, and the estimates have to be based on more analysis than "1%-3% above the company's guidance". If the stock is more volatile because analysts' estimates are more widespread, then so be it. Investing in stocks is risky, with or without guidance--as companies who radically miss their numbers frequently illustrate.
The whining about guidance, in my opinion, is actually just frustration that the Google goose is no longer laying golden eggs.