in the comment of ssvsetup in reginstall.cpp:

// Run the code in the SSV DLL to perform registry key redirection.
// This serves two purposes. One is to support installation of the JRE
// while the web browser (IE) is open and detection of that JRE
// without restarting the browser. The second is to perform the
// redirection of the HKLM registry entries on Vista to cover the case
// where UAC is off; the HKCU redirection performed by the ssvagent in
// medium integrity doesn't have an effect in this case, and we want
// to try to avoid launching ssvagent in high integrity mode. Since
// we're already high integrity at this point, do this work eagerly.


Note that the above comment was referring to a bug in Vista fcs which was fixed in SP1.
we should investigate the ssv module to not setting the redirect keys in the HKLM branch.