The cable companies are pushing for this.
I do know that it has been brought up in verizon's internal newsletter.
Not a direct quote but the gist is this:
Verizon will not be doing any metering of internet usage. We will let the cable companies meter theirs and when their customers leave them in droves Verizon will welcome them with open arms and absolutely no metered restrictions!!
This includes Verizon's FIOS and Verizon's HSI (ie DSL service)
The main reason the cable companies and are going to the metered system is because (as the article states) they are structured differently meaning people "share" their bandwidth with everyone else. Personally I wouldnt use a cable co. for my internet even if it was free.....WAY to many issues