I have to confess that I heard about the dataportability movement a couple months ago, but to be honest I can't really get my head around the concept. I would love to have someone explain this to me in terms I can understand.
The way I perceive it is that in the current environment each read-write web site we wish to participate in requires us to set up an account and generate a profile. The concept here seems to be that once you set up an account at one site you can then take that information to any other site without jumping through the hoops of generating a new profile.
This push seems to be going hand-in-hand with the OpenID concept. This would eliminate the need to actually set up individual user names and passwords for these various sites. I like this concept because it would eliminate the need to try and remember the login data for all my sites after I accidentally clean the cache of my browser. Again, here's a video that explains it well.