Someone apparently overheard Tim Cook telling an Apple Store team member in Berlin that he wears his Apple Watch everywhere, "even in the shower." Somehow that bit of gossip got posted to the French site iGeneration. From there, the story got picked up and translated (via Google translate, I presume) by the U.S. Apple-centric sites. I first saw the news on Apple Insider which, to their credit, labeled it as a rumor.
The only thing I can recall reading on the matter is what David Pogue wrote after attending the unveiling, under a section he titled 'What Apple said privately'.
For example, the Apple Watch is water resistant. Sweating, wearing it in the rain, washing your hands, or cooking with it are fine. Take it off before you swim or get in the shower, though.
My guess is that Apple, at that time, was still working out the level of water resistance. Apple probably knows by now (actual water resistance level and what they want to advertise).
So is the Apple Watch showerproof? Maybe.