Thanks to reader Brendan Wilson for pointing this out: The Palo Alto Medical Foundation is warning against the use of Google Desktop (and presumably, any similar search tool). The foundation even published a FAQ about GDS. From that document:
How does this affect me? If this tool has been installed on a PC that you are using, it is possible for your private health information viewed through PAMFOnline to be cached on the computer’s hard drive and retrieved later by someone else.
What can I do about it? If you uncheck the “Include Secure Pages (HTTPS)” option, the tool will no longer be able to retrieve secure PAMFOnline pages.
This is one example of what I am sure will be a long, slow awakening to the power and potential of having search history in our lives.