A team from St Petersburg have developed a brand new Raspberry Pi-powered board that enables you to use two Pi cameras at once. Called Stereo Pi, the board is a Compute Module carrier that takes any model of the Compute Module and breaks out two CSI interfaces into which you plug the cameras. The board is compatible with both the command line scripts (raspistill/raspivid) and also the picamera Python library. There are multiple versions, including the one pictured which breaks out the GPIO to a standard 40-pin header, allowing you to wire up buttons to activate the cameras etc. Pledges start from $69 (sorry, missed the Earlybird!) with free ground shipping (although for that one you don’t get the ‘taller components’ and you need to provide your own Compute Module while a full kit (which includes a CM3 Lite) will set you back $125.
I think they’ve pitched the price of this one right – it’s something not everyone will want to do, so they’re not looking at massive quantities, but that’s a pretty good price for a CM carrier board with the ability to do two cameras in small package.