UPC Ireland have had this for a while on their Infinity DVR/WiFi boxes. They are rolling it out as an o/s update for their older routers now. They sent me an email about it, which tells you how to opt-out.
Opting-out is the first issue, it should be opt-in. That assumption by big business STILL hasn't been fixed. Second issue is that you have to log in to your account online, and click on a button to opt-out - you don't do that on the router itself.
A few years ago I would have said that sharing a small part of your WiFi was a public-spirited act. Now, It's just another way for yet another company (your ISP) to track your movements.