a lot of buzz around Data Portability those days but I'm afraid that it will result in no-ending discussions with nothing concrete in a near future. I hope I'm wrong and I totally respect all those peoples way smarter than me which represent Big Actors of our actual Giant Global Graph. Besides that, my main priority is not Data Portability but data ownership, once we've got the power data we'll see how to share this with other applications and how to deal with privacy.
A Semantic Web Data Space is a container for domain specific portable data, which is provided in human and/or machine friendly structures. Data in a Data Space can be referenced by an identifier, and is linked with other data across spaces and domains, and thus can be viewed in an Object Oriented fashion.
APML allows you to share your own personal Attention Profile in much the same way that OPML allows the exchange of reading lists between News Readers. The idea is to compress all forms of Attention Data into a portable file format containing a description of your ranked interests.