Talk about clichés.

There we were, waiting ages for a cross-platform device to soak up and share our profiles from social networking sites and suddenly three turn up at once.

Fortunately, the three in question all have tremendous potential. Google Friend Connect, MySpace Data Availability and Facebook Connect take some of Facebook’s most endearing original features - the option to port in your contacts and third party API’s - to the next level, allowing you to create a kind of unified, “webwide” profile.

The premise of all three is that your personal data from one site can be securely shared with another, so, for example, with Facebook Connect you can pair up your Facebook and Digg profiles. MySpace now allows you to share your identity with Twitter, Yahoo and Ebay (with more to come). Google’s aims, naturally, are even further reaching… they want to create the protocol by which people store and transport their personal data.

The portability of data is nothing new, of course – Facebook’s API has been sharing your data with third party developers since 2006 (with your permission), but the new offerings take this idea to the next level. Facebook describes Connect as allowing users to “bring their real identity information with them wherever they go on the Web”.

There are definitely benefits for website owners. Google’s technology is being made available for developers to use in their own sites, making it easier for users to “get started” on a new networking site. Facebook’s strength comes from the fact that almost everybody seems to use it – imagine being able to “borrow” organically constructed networks wholesale.

These tools are going to change the way we use the internet. They are a huge step towards the idea of a unified online presence for the individual.

But the three projects are not without their problems.

Facebook have thrown a spanner in Google’s works by not allowing access to their records over data protection concerns. Admittedly, this seems to be a temporary glitch, as greater integration is in everyone’s interests.

More importantly, do we really want to create a single, unified online presence? Personally, I’m not sure. How many people choose to use the same username and avatar for every forum on which they post? Facebook, MySpace, Flickr, Bebo - all of these sites offer plenty of opportunity for users to link to their profiles on other sites, but how many people choose to do this?

For better or worse, one of the great appeals of the internet for many people is the option of cultivating multiple personae, so you have a different location to visit according to your mood. This won’t, however, stop Facebook Connect, Google Friend Connect and Data Portability from being hugely successful. They will change our interaction with the internet for good.

The unspoken goal of all three is to encourage users to store the most valuable 21^st century commodity – personal data – in a particular place by making it easier to do so. But how much should we really be sharing?