Valve have distanced themselves from Xi3's Piston, the small form modular PC that's now available for a pricey pre-order. Piston was originally revealed at the Consumer Electronics Show in January, where Xi3 announced that they had received an investment from Valve. But in a statement to Eurogamer, Doug Lombardi states they're no acting as the mini-PC's benefactor.
It's not the "Steam Box", but Piston - Xi3's living-room friendly small form PC - is a box with Steam in it. Technically all PCs have the potential to be boxes with Steam in them, but most aren't designed both specifically for gaming and to fit in the palm of your hand. In fact, I've just attempted to lift my PC with one hand and now my fingers hurt.
At this weekend's SXSW Gaming Expo, Xi3 unleashed pre-orders of the device. It's a pricey proposition: $899.99 gets you the base version, with 8GB RAM and a 128GB internal solid state hard drive. And that's the special SXSW price. When the expo ends on March 17th, the standard cost of $999.99 takes effect.