It can look absolutely silver if it's in a particularly bright sun-lit room. I suppose it can be any shade you want it to be....
I was flummoxed by the "space gray" color when I first saw it in the Apple Store. After watching it change shades in several reviews, I began to understand why. It would be cool if Apple created a kind of "light show" display in the stores that played off of the reflective qualities of the cylinder while also calling some much needed attention to it, as it's so tiny that I almost didn't see it!