Windows 7 Homegroups requires IPv6 to work correctly. Thats about the only use i could see for v6 at this point, and you can run both v4 and v6 at the same time even if your router doesn't support it as long as the switch does your still ok for local traffic.
Switches and routers don't need to support IPv6. A switch doesn't know or care what layer3 protocol is being used. If you truly need to ROUTE v6, then sure.
But no home user has any reason or justification for needing to ROUTE v6. This whole conversation makes my head hurt.