Whitewashing is the blog of Benjamin Eberlei and covers topics in software-development and object-oriented-design. Benjamin works for Qafoo and you can book him for consulting and trainings.
The application retrieves and stores bookmarks on your own tent-server, nothing is kept on the applications server and as a user you keep full control over your content (bookmarks).
About two month ago a new distributed social networking protocol was launched called Tent.io. It works over HTTP using JSON and distributes data using webhooks. This happened in the shadow of app.net funding, just two weeks after they collected over 500k USD. Tent.io got lots of attention but not as much as app.net sadly. Its distributed nature however is much more suited to achieving true independence of large companies and true privacy for the users though. Compared to Diaspora it has the benefit of being a protocol, not an application first.
Now two month later, there are reference implementations for Server, Client and a Twitter like Status application. You can use Tent.is to create a free or payed tent account including access to the status application or setup your own tentd server on Heroku.
As a user I can connect any application to the tent server I have registered with and control the visibility and sharing policies. Content can be private, public or visible to certain groups only. A Tent server then makes sure to distribute content to the appropriate subscribers.
In this early state of the protocol it makes sense to register on the central tent.is service, however when the server gets more stable or alternative server implementations popup its easy to move all your data off tent.is to your own server. One feature that will hit tent.is soonish is registration of domain records. That will be the first step to your own tent server, I am eagerly waiting to host all my content at https://tent.beberlei.de at some day.
Right at the moment the tent software stack is developed by the team that also hosts Tent.is. If all you can provide is money, then signing up for the 12 USD per month is the way to go.
If you are a developer, then take a look at the Wiki where related projects are listed. You will find a bunch of client libraries for major languages already, helping you to get started.
I suppose the major work lies in implementing Status-Post clients for all major smartphone platforms and desktops. As well as the host of applications that Facebook and other social networks provides: