Our understanding of IPv6 deployment is surprisingly limited. In fact, it is not even clear how we should quantify IPv6 deployment. In this paper, we collect and analyze a variety of data to characterize the penetration of IPv6. We show that each analysis leads to somewhat different conclusions. For example: registry data shows IPv6 address allocations are growing rapidly, yet BGP table dumps indicate many addresses are either never announced or announced long after allocation; Netflow records from a tier-1 ISP show growth in native IPv6 traffic, but deeper analysis reveals most of the traffic is DNS queries and ICMP packets; a more detailed inspection of tunneled IPv6 traffic uncovers many packets exchanged between IPv4-speaking hosts (e.g., to traverse NAT boxes). Overall, our study suggests that from our vantage points, current IPv6 deployment appears somewhat experimental, and that the growth of IPv6 allocations, routing announcements, and traffic volume probably indicate more operators and users are preparing themselves for the transition to IPv6.