I also enjoyed that combined social feed in Harmattan. Should be possible to reinvent and even improve upon. While N9 code for that was likely closed they might remember how to do it or steal from Gwibber or something. How I'd like the N9 social feed improved on Sailfish would be the ability to reply or retweet or such without pressing and opening a separate application. We had a statusnet addon written by the community, I could use that again and diaspora would be nice. Maybe eventually pump.io