The Data Portability Project have come up with the idea of a data portability policy, using the metaphor of the privacy policy which most companies now use.
The idea is not to dictate a given policy, but simply to be open about it. It’s a nice idea: many web sites and companies are not up-front about what data (if any) can be exported from their site and let the users attempt to discover this by themselves. Even companies that in other ways win respect are often guilty of this – for example Opera’s myopera.com social network does not have a mechanism to either export or backup data that is placed there. Does our webmail system allow the download and backup your messages? Does our browser permit us to export bookmarks? How many of us check these things in advance, before beginning to use a product or service?