For those that dont know, the Raspberry Pi is a $35 computer on a self contained board with a Broadcom SoC with a 700 MHz ARM 1176JZF-S processor, 256 MB of RAM, Ethernet connection, dual USB ports and a SD card slot.
It has sold in bucket loads, with a healthy waiting list just beginning to clear. Applications for the Raspberry Pi are legion and this one is the first I've seen that turns it into a synth.
The UK based modder in question who remains enigmatically known as Raspberry Pi Synthesizer on Blogspot has built a single OSC synth in software. You can see the results of his ongoing experiments on his dedicated blog.
Using Chains and automation to switch keyboard setups
All the modules in the miniMOD range together in a standalone keyboard