[snip]Thanks for the plug Tim. I wrote a draft on a gateway translating between IPv4 and IPv6 multicast. It's expired now, but you can find it at http://www.uninett.no/testnett/multicast/mcgw/draft-venaas-mboned-v4v6mcastgw-00.txt
This solution was implemented 18 months ago, and has been in daily use by several people since then.
Are there more appropriate places to take it?