I've received those with my Nexus 4, about 10 days ago. I've ordered the phone via the French Google Play and I've apparently been lucky enough to have a device from the new batch: the phone has the two small rubber "nipples" on the back (to lift it a little and avoid slippery) and the headset was in the phone box as well.
They come with 3 ear size adapters and have absolutely no brand on it or on their little plastic bag. They do have a small "CE" symbol, on the plastic around the 3.5mm jack, simply meaning that they've been approved by the European Community safety standards.
My guess is that it may be an European or French addition to comply with local laws, either to prevent exposition to radio waves (French DAS law) or to provide some safe-driving option out of the box... Anyone received those yet outside of Europe?