I think cubie has a website with all kinds of software packages: http://cubieboard.org/download/
The control unit should be low budget, powerful enough to drive at least 4 Prismas (better would be 5, then you only need two control units for a set of 10 Prismas), easy to put AM's cgminer version and a miner OS with web-GUI on (meanwhile I think Minera looks more promising than MinePeon, which hasn't been updated since March).
This all is very exciting, but time consuming for me as I don't have enough time to follow my hobbies right now. As said before, it does not make sense for every Prisma buyer to reinvent the wheel himself, and I have hopes that someone will step up and prepare a ready to use image with Minera + AM's cgminer version for Prisma, then I would just buy whichever controller hardware is supported.
so if you run four R4s with 4 Pis, then one Cubie A10 is cheaper than having to buy 4 Pis. (you can'r run 4 R3/4s with 1 Pi for ex.)
with Tubes/Prismas, it may be a similar situation, but until we have tested this thoroughly, we just don't know yet.
and also, you can use whatever you have to run cgminer, it's not necessary to go out and start buying Pis or cubies to run prisms... if you have a laptop or a system that can run cgminer, you can use that...