Data portability aims to have an open standard which allows the user to have one profile across all the social networks like Facebook, Wordpress, MySpace, del.icio.us and all the others. Dataportability.org: "As users, our identity, photos, videos and other forms of personal data should be discoverable by, and shared between our chosen (and trusted) tools or vendors." Dataportability supports APML (Attention Profiling Mark-up Language), a mark-up language which compresses all our "attention data", quasi our meta data, into one file. From the marketers point of view, I am not quite sure about the idea of data portability because I think the big players like Facebook have huge communities and most of all the profile details of all the users. Therefore, I do not think that they want to share these details with other communities. However, it could be a new way to even better detect customer's needs and thus customize services.
Check out this cool video about data portability: