My mother-in-law brought this back from the grocery store in France last summer. It's called a Bib'Evian, and it's an adapter so you can put a regular nipple on a bottle of Evian.
It works on other water bottles, too, as long as the cap opens with just 1-1.5 twists. [Tried it on Diet Coke-size bottles and other water brands; so far, it only works on Evian.]
In France, the Bib'Evian accompanies a case of bebe-size (33cl) Evian bottles, or you can buy it separately, with just mini-bottle. I can't find any mention at all about its availability outside France. We threw it in the bag with a couple of one-serving formula packets, just in case there's a bottle emergency--but no bottle.
French parents praise it, suggest using a different nipple, and complain about the cost of feeding their kids Evian. [Hey, Manhattan parents are working 100 hrs/wk just so they can bathe their kids in the stuff, so shut your tarthole, Pierre.]