So far as I am aware, this is default behaviour only on certain versions of Mac OSX, and must be explicitly enabled on all others. Manually, on the console. RA does not dynamically distribute this behaviour; the client has to choose it. Usually it is a sysctl or a registry variable or the like.
NIT: Add any IPv6 capable Windows "workstation" to that list (workstation meaning "not server" OS). Or any USAGI-derived 'nix kernel, AFAIK. (WinXP as described/expected, Vista with a twist (no EUI64 by default))
The philosophies of design of these two systems are entirely at odds.
While I agree with that statement, I disagree just a little bit with your supporting argument. On either case, the host is initiating the discussion and trying to do what it wants (either appending randomized IIDs or asking the DHCPv6 server to supply it with randomly generated IIDs, and using the results as "(a) temporary/privacy address(es)") ... in either case, if the hosts doesn't support it or doesn't ask, it doesn't happen. /TJ