I found this lengthy article on the subject: https://lwn.net/Articles/544347/
I agree that ultimately, Identi.ca just felt like a Twitter clone. Although it's free and federated, I didn't feel it reached it's potential because there was only one site to sign up to. Start my own server? Not an option financially for me, atm, and I don't know of any free-to-join alternatives. OStatus is great, but isn't setting a huge example yet.
Pump.io doesn't seem like a step backward to me. Sounds to me like a new chapter in future OStatus history, because the more OStatus experiments out there, the better. The backslide to Apache is disappointing, since AGPL clearly protects your freedom on a server much more effectively, but I guess you have to accept SOME non-GNU licenses online or you'll hardly use anything (for now).
I'm more interested in this off-hand reference to "free Platform-as-a-Service (PaaS) provider[s]" AppFog and OpenShift. Is it actually possible for someone to set up their own social networking instance while hardly paying a cent? If Pump.io accounts will eventually be run by individuals on their own free servers, I see the future of federated social networking being very interesting, and if I could set up my own StatusNet instance right now completely gratis, I may just jump on the chance.
