Comcast is planning on giving each customer a /56. That's 256 64-bit subnets.
You'll still be able to use a router/firewall, although it likely won't do NAT on IPv6. Hopefully Linksys/Netgear/etc. will get off their asses and produce some good IPv6-compatible home gateways within the next couple years though. They're probably waiting for ISPs to make the first move.
