TimeWarner and Comcast have both done it toe. TWC did of to let me know of a TOS violation and Comcast uses it as part of their setup. If you don't allow them to hijack DNS and show you things that you have to click through, you may find yourself unable to route traffic at all until you call them. I've dealt with this with every move in CA (about a half dozen times) and my move to TX. Seems pretty likely to me.