It would be nice if ISP's offered the option - and they certainly easily could - but you can do it yourself if you want:
I just set one up on Friday. I bought the $75 Raspberry Pi Canakit (has everything you need except a USB mouse and keyboard that you need to temporarily plug into it while you set it up) and had it up and running in less than an hour for my entire house.
It makes a noticeable difference, notably on page load performance especially on my iPhone, which has always had a sorry adblocking situation.
Looking at the stats at http://pi.hole/admin (the internal URL admin page) it's blocked 5,151 requests out of 27,168 (~20%) in just two days.
Next step is to set one up in the cloud as a VPN/DNS server so I can route my outside-of-home traffic through one as well.