Linux seems to be a great platform for these little embedded devices. It’s small enough that it can fit in economical hardware, portable enough that you can put it on almost any processor and platform, and it’s got great networking tools. This particular bot runs on Linux Mipsel devices (“Mipsel” is the port of Debian Linux on MIPS processors). More here
They’re calling it the first botnet designed for broadband equipment and routers, and that it is. But it’s the first of something else: psyb0t, the first Linux botnet.