To play devil's advocate, who is using 6to4 in a notable deployment?
At Sun we are using 6to4, as an early transition mechanism, for our
deployment. For the past few years we have had a few (read 3)
engineering sites connected by configured tunnels. We found deployment
scalability problems with this approach, so we decided to go with 6to4.
Why? In these tough economic times, were it is near impossible to
convince cost constrained IT departments to upgrade their core routers,
6to4 becomes the poor man's solution. We are in the process of creating
10-15 6to4 sites which will consist of engineering and labs groups.
Unlike configured tunnels, new 6to4 sites can be added at will, instead
of having to dig a new configured tunnel for each site. When Alain and
I explained how configured tunnels might work, the IT folks turned green
remembering deploying multicast. :)