Technically Nexus devices have always been "at cost" to Google, since it's the OEM who gets the profit off the hardware sales in exchange for Google controlling the experience. So Rubin's statement about "selling through" the Nexus 7 actually says very little since that's always been the case. The real issue (and what the media is mostly missing) is whether ASUS is selling it at a loss or not, and considering the Memo the Nexus 7 was refactored from was originally going to be sold at $250, it seems unlikely.
I think they might. Carriers get part of the 30% share of Play sales if you have a cell phone, but I don't know who gets that for WiFi tablets. OEMs getting it is certainly one possibility (Google keeping it is another, of course). There's similar revenue sharing for some of the search traffic as well, IIRC.
