So how many people "clean" their satellite navigation device before selling their car? According to this article, you probably should.
Google has admitted that it has been collecting - apparently without intent - private information (snippets from emails and on-line activities) from public Wi-Fi networks in connection with its Google Street View mapping efforts. (Google was also mapping public Wi-Fi networks as part of Street View). I have previously posted, there is great value in the street level imagery that Google is collecting. However, one can certainly appreciate the privacy concerns associated with any organization collecting this information - even if it was being sent over public (and presumably unsecured) Wi-Fi networks - particularly if the information was being collected as part of a broader mapping effort.
For those interested in a well-rounded technical discussion of the issues associated with data sharing, I would recommend reading Peter Batty's geothought blog. It includes a link to a video of a roundtable discussion from GITA 2010 with a number of deep thinkers in this area, including Peter (as moderator), Steve Coast, James Fee, Andrew Turner and Ron Lake.