out of curiosity .... why are some people bothered that their MAC or rather a modified form of it is out there due to the NORMAL workings of stateless auto configuration RADVD OR RTADVD?
are you also going to be manually setting the ipv6 ip of your tv, sat tuner, o!play, fridge, 2 laptops, ps3, nas box, xbox, network radio, toaster, oven, electric and gas meters, switchable bedside lamps etc etc and the 100 other network items youre going to have at home in 10 years time never mind already!
this is how ipv6 and router announcement works
there is of course no reason why you cant manually set the ipv6 ip of your devices or phone (and I do for servers so they have very very identifiable easy to remember IPs) but back to the orig question ... why would you, other than pure paranoia?
I would be more worried about not having an ipv6 firewall
iptables is there in 2.1 but I've not seen ip6tables yet
you really dont know what some of these apps are doing _phoning_ home eh?
something like LittleSnitch on the Mac (OS X) would be nice