From the various public threads we know that:
It will be RoonSpeakers, probably in November
Raspberry Pi can run RoonSpeakers, act as a DSD stream endpoint and drive headphones without a case
Squeezebox as an endpoint is intended
The underlying protocol is called Roon Advanced Audio Transport. An SDK will be released to manufacturers who will develop firmware for RoonReady devices. Software apps/packages, called RoonSpeakers are planned for mac, pc, android, ios, linux, rpi.
What the Roon team are attempting here is a brand new digital audio protocol made available without licence fees and deployed across the whole gamut of operating systems and hardware. The support for the RPi and Squeezebox should warm the cockles of all digital audio enthusiasts hearts. If they get it right (and I wouldn’t bet against them) then RAAT will be the new de facto streaming standard to be included in all new hardware.
I suspect that manufacturers will be writing RAAT firmware promptly as soon as they see their competitors doing it and customers asking for it.