Well, there's a really good article on The Verge
all about it. Apparently the pricing is due to being manufactured in the US. Makes sense, actually, and Google seems to have a typically nonchalant attitude about how well it does, describing the whole thing as an experiment. At least they're not crazy.
It still leaves me thinking they should have added more functionality to make it more of a premium device; something that isn't mimicking the mass-produced Foxconn gadgets. But one part of the conference stands out to me. When they were talking about Nexus Q, they said they wanted to make it as hackable as possible. Perhaps some developers will pick this up, or Google will donate a few to the various ROM developers out there, and it'll turn into something awesome.
At $300, I still doubt it, but hopefully it will avoid being so much of a bust that it doesn't work as a proof of concept. Definitely would love to see more companies trying out this model.