What do you think of things like ostatus and technologies around http://www.w3.org/2005/Incubator/federatedsocialweb/wiki/SWA...?

There are a couple of considerations for me:

3rd party (particularly commercial entities) vs personal ownership of user data and identity seems like a nail which is quickly coming into focus a) with the ways that people are wanting to use social media and b) in light of recent privacy and monitoring revelations.

The kind of use cases above in SWAT, combined with p2p network effects seem to offer a glimmer of far more powerful functionality than any closed platform, however large, could ever keep up with (just as we see open source eat proprietary competitors through sheer scale and subsequent pace of innovation).

My instinct is that the federated technologies suffered from being ahead of their time and will get picked up again at some point.

Yeah, this is definitely true. You can see the trend even in networking, where the routing protocols have typically been very decentralized in nature. Now with the advent of OpenFlow and data center networking we're starting to see a shift towards centralized control of network routing.

file sharing? pretty big nail. a decentralised system supports easy access to files considered to be obscure or "long tail". unless you want to say that bittorrent is not a decentralised system.

Amazon S3 would be a much better choice for files considered obscure. A well designed decentralized system will have to spend a decent amount of effort to ensure that the long tail files don't drop off of the network. If you want fast access speed to those long tail files, now you're going to need even more redundancy to overcome access bottlenecks.

bittorrent allows a more ad hoc approach that gives results, whereas there doesn't appear to be financial incentives for someone to pay for amazon s3 to provide the same.