Purely the carrier's fault, which is hard to see from the article. In Australia (I'm on Telstra) my GNex was supplied with 4.0.2, and a couple of weeks later was bumped to 4.0.4.
Yup, the fault lies entirely with the carriers. Also in Australia, bought my GNex from Optus in December, shipped with 4.0.1, bumped to 4.0.2 a month or two later, nothing since.