Passing through the Habu Textiles booth at Stitches West one year, I looked up, saw a sample of this "sweater", and said, "That's a River Tam sweater and I must knit it."
It's knit from silk and stainless steel (no joke) thread, it's code name was "The Impossible Unsweater Project", and it was a royal pain in the ass to knit, it's stretched out is weird unpredictable ways, and I'm still pretty damn proud of it.
Ravelry Link:
stitchbug's River Tam