There is no link between RedMatrix and Matrix.org - the fact that both have Matrix in the name is total coincidence. On the Matrix.org side, we came across RedMatrix for the first time a few months ago when stumbling across http://lists.w3.org/Archives/Public/public-fedsocweb/2013May... in Google, which then linked from Friendica/Red to RedMatrix.

I've never played with Friendica/Red/RedMatrix/Zot, but from what I can see, it's more about federated blogging/social networking than messaging or pure JSON synchronisation like Matrix. Architecturally I'm not sure how they compare - I only just found https://github.com/friendica/red/wiki/zot; we'll have a read and see what the difference is.

Something we're very keen to do with Matrix.org is to build as many gateways and bridges through to other comms ecosystems as possible - so the fact that both Matrix.org & RedMatrix (& Diaspora & Identi.ca & all the others) are operating in a similar space isn't at all a problem - so long as they all talk to each other. It'd be a bit embarrassing if we were building federated communication systems which couldn't gateway to each other!