In a mea culpa heard round the online world, Google apologized for disregarding users’ privacy concerns in the launch version of its Buzz social media application. It then tweaked it for the second time in a matter of days to mollify an army of irate users.

This re-vamp, which makes it easier for users to control who is following them and whom they are following, comes after allegations that Buzz is too intrusive. As the Guardian reports, one blogger takes the search engine to task for unwittingly revealing the identity of her current boyfriend to her “abusive ex-husband.” Even the Geek bible, Wired, admits to having “mixed feelings” about Buzz. It set up a type of Buzz meter where readers can vote on trending Buzz transgressions. The top vote? One person calls for CEO Eric Schmidt’s head, saying:

Whoever made the decision to make all our contacts visible to all other contacts in Google Inc. should apologize profusely, because that person doesn’t have a clue about what privacy means. If the person, even if it is the CEO, doesn’t apologize, he/she should be fired.

The problem, as Google is finding out the hard way, lies with how the public regards email. Like snail mail, it is by nature a private affair. And while it may seem that social networks have created a me-me culture of extroverts, Google Buzz is proving there are still limits to what the typical internet user will share.

Social networkers have learned to compartmentalize their contacts, setting up a hierarchy of strong and weak ties. Automatically adding social network features to confidential email is considered, by some at least, a breach of trust.

As the New York Times reported just as the controversy was gaining steam, “e-mail, it turns out, can hold many secrets, from the names of personal physicians and illicit lovers to the identities of whistle-blowers and antigovernment activists.”

With so many privacy concerns swirling around Buzz, you have to wonder if Buzz will now get a chance to pitch this as a collaborative enterprise tool for corporates.