I'm trying out Diaspora and looking at Frendica and it hits me that cross-posting is not the entire solution to the fragmenting social web, cross-receiving is essential.

I don't want to post to Twitter or Facebook or Google+ I want to post my thoughts to an open source, federated, platform, but, I do want to read what others post to all of the various other social networks. Preferably without having to have to login to all (or even have an account any) of them.

How to do that? There's an exercise left to the reader. I'm still thinking it through. Obviously you could create mirror accounts on your chosen social network that scrape content from the other networks and feed them into yours, but how you could reply? Do they need to mutually cross-recieve you? How could you send a private message? Twitter and Facebook killing RSS makes things difficult too.