This is, of course, a direct competitor to Google's Friend Connect and Facebook's Facebook Connect, though, as Steve O'Hear notes on ZDNet, there are important differences between these projects. While Friend Connect relies on an iframe to exchange data between sites, the Data Availability APIs makes third-party services request the data from MySpace 'on the fly' and only allows a user's login name to be cached.

As Steve notes, if MySpace's Data Availability API is adopted by a large enough number of sites, it could make MySpace the de facto host for social network profiles.

The details around Facebook Connect are still a bit unclear, but Facebook will probably update its developer community about its plans at next month's F8 conference.

For users, being able to have their profiles linked between different services is a major step forward in terms of usability. It would be very convenient to have a Twitter profile automatically synch with a MySpace (or any other service's) friend list, or only having to update photos on Photobucket and then see them directly on MySpace.