Yes, Comcast provides v6 PD prefix(at least in bay area), which allows every v6-capable device in your home to have a v6 address. if your router is a bit outdated and doesn't support v6 with factory firmware (as my TP-Link router), I suggest to use openwrt 12.09(dhcp6c + radvd)
I have been playing with Comcast IPv6 at home. Being able to request a /60 is great. I can have 16 x /64 subnets on my home network. This is going to be an interesting transition for a lot of people who are used to IPv4 and NAT.
If anyone has Comcast and wants to play with IPv6, I recommend setting up a pfSense firewall/router. It has been a good learning experience. http://www.pfsense.org http://www.youtube.com/watch?v=N6vT3_2PO1w
Note that you need an IPv6 capable cable modem & router. Recent cable modems are mostly capable, and most (all?) Apple routers are.