FYI, we've released "IPv6 toolkit v1.2": a set of IPv6 security
assessment tools that were produced as part of a project I carried out
on behalf of the UK CPNI. The toolkit compiles/runs on *BSD and Linux
(and probably on Mac OS, too).
This toolkit can be employed to perform local IPv6 scans, assess a
number of security aspects of IPv6 implementations (such as
predictability of Fragment ID values), etc. It can also be employed to
play with IPv6 address resolution, SLAAC, etc.