The latest hot rumour in the world of social networking is that Google is developing what some industry insiders are calling a "Facebook killer" - a new Google-run social network, patterned after Facebook, codenamed "Google Me."

With more and more bloggers lining up to speculate on the rumor, and even major newspapers like The Independent weighing in on the buzz, it's seeming like a more and more certain thing that Google is, in fact, creating a social network designed specifically to rival Facebook. There's just one problem, a problem that's going to doom Google Me to fail in the same way as most other social networks have failed: everybody's already on Facebook.

The thing about social networks is that they need to have a certain critical mass of users, or other users won't join them. If I have to choose between two social networks (let's say, for the sake of argument, Google Me or Facebook), chances are slim that I'm going to choose to use a social network that none of my friends belong to. No, what's much more likely is that I'm going to join the social network that all of my other friends are already using - in this case, Facebook.

It's not a question of features. Other social networks have certainly been more fully-featured than Facebook, but they haven't succeeded. The reason is that Facebook has already built up a critical mass of users - at this point, over 400 million - and those users attract their friends and family members to the network. Even if a better, superior social network pops up with better features, a better privacy policy and a sleeker interface, it's going to be lacking in the one critical thing that all social networks need - you.

Getting social networks up and off the ground is a tricky thing. When Google launched their "Google Buzz" microblogging platform earlier this year, they thought they could sidestep the issue of not having any users by simply automatically forcing Gmail and Google Accounts users to join the Google Buzz social network - but that strategy blew up in their faces and resulted in Google being forced to make a public apology about their aggressive recruiting tactics.

However Google plans to get its "Google Me" social network off the ground, it's going to be a painfully slow start. Quite possibly the best way for them to recruit would be for them to allow users to import their friends from Facebook and invite them to Google Me, but that violates Facebook's terms of service. Google can offer to let users import their Gmail contacts into Google Me, but they need to tread lightly - it's only been a few short months since Google got busted for automatically importing Gmail contacts into Google Buzz, a practice which was widely decried as being an invasion of privacy.

Although there still hasn't been any official word from Google confirming or denying the existence of the"Google Me" network, that silence can be taken to indicate that it does, in fact, exist. According to people who claim to be familiar with the project, Google is working feverishly to finish it up in time to give them a fighting chance against Facebook, who is now expected to break one billion users. Whether or not it's already too late for Google still remains to be seen, but from the perspective of user mass, it's looking pretty uncertain.