Had a look around and couldn't find anyone doing this ?
Just for fun, I thought it could be an interesting project ? I have a bunch of arduino mini pros.
By crossing over the i2i on the first one in the stack - they should then be able to be stacked on top of each other with regular stack headers.
So you end up with a sandwich of say, 10 pro minis.
By incorporating some code for them to randomly or sequentially step through i2c addresses they should be able to establish communications with the master.
You could then write some example code to have the master farm out stuff for the other 9 slaves to do, and assemble the answer ?
It's hardly going to be a render farm, but though it'd be a fun programming challenge. Ideally you'd want the same code on every board, and for one to 'grab' master on startup, they all then configure themselves automagically, and the actual 'job' can be farmed out/controlled by the master over the i2c bus (running at 400).
perhaps could get something like a beowulf cluster running ?
worth a play ? or has it been done already ?