All IPv4 address space was allocated to regional authorities by March, 2011, and exhaustion of these allocations looms. When exhaustion occurs, there will be no room left for further expansion of the Internet, and/or increasingly problematic uses of NAT, with application failures increasing with time. IPv6 has existed for a long time, but has not been widely deployed in home routers, and since usage has been low, networks may have latent problems that need to be fixed to enable a seamless transition to IPv6. Recent trials of IPv6, including World IPv6 Day, have shown that IPv6 transition is feasible and desirable.
CeroWrt has IPv6 (specifically 6to4) networking enabled by default. If the router has a public IPv4 address, 6to4 will be enabled on startup, and all your local networks supplied with a usable IPv6 address range. 6to4 is working well on some networks in America, notably Comcast, on which geographically dispersed production 6to4 relays have been installed, and much of Europe, but may be (possibly very) problematic in parts of the world unserved by local 6to4 relays.
IPv6 can be easily disabled or modified via the router's networking screen, on the 'v6' option, but please try to report bugs and expend the effort needed to actually use it. The future of the Internet is at stake!