It's not an official confirmation but it's probably about as close as we'll get for now.
Rumors of Valve's plans for a Steam Box console have been doing the rounds for a while now. Things got started back in February when Gabe Newell said in an interview that while Valve had no reason to believe it was any good at selling hardware, they had to continue to innovate, and if that meant developing and selling hardware, then so be it. Today, a job posting points to the existence of said hardware, which could be either a game console or a PC.
A job posting for an Electronics Engineer over at Valve says in no uncertain terms that the company is looking to get into the hardware game.
"For years, Valve has been all about writing software that provides great gameplay experiences," the post reads. "Now we're developing hardware to enhance those experiences, and you can be a key part of making that happen."
Just in case that leaves any room for doubt, the posting continues, "We're not talking about me-too mice and gamepads here – help us invent whole new gaming experiences," with an invite to join a "highly motivated team that's doing hardware design, prototyping, testing, and production across a wide range of platforms."
Valve says interested applicants will be required to have hands on prototyping experience, lab and measurement skills, system-level design experience, knowledge of embedded systems/microcontrollers, experience with high speed serial interfaces, experience with schematic entry, and experience with circuit simulation. Additionally, the company would like if the candidate also had an idea of doard layout (analog and high speed digital), Hardware Definition Languages (HDL) for FPGA and chip design, and a whole host of other things (including experience with thermal management and ARM / X86 system design).
Hit up Valve for full details. There's also a screenshot below in case the job posting is pulled (click through to zoom).