It’s pretty simple – the online desktop is this task list. Which is just a start (please add more!). It isn’t a single product you can download, though we’ve been working on prototyping components such as the GConf synchronization, a new sidebar, etc.
I’m excited by discussion like this that shows developers are interested. If you are looking to jump in – a really cool yet discrete project would be implementing the pick-a-service dialog from that todo list. In other words, the thing that should appear from F-Spot if you plug in a digital camera, but don’t have a photo site in your accounts.

Right now, you can get a person’s contact network from the data model, and then enumerate the “external accounts” (sites used) by those people. In fact, this is exactly how the BigBoard Photos Stock works. What you’d need to do is have some way of tagging services by what kind they are (e.g. photos). Then code the widget to query those, uniquify it, order it by some criteria, then just stuff it all in a treeview.