We've received several notes of confirmation regarding our previous report where systems have the option to "allow other devices to browse files on this computer" turned on by default.
Though this option may pose a security risk in some instances, the issue is essentially null since the "Shared" folder is the only accessible directory in all of the case examples we've received so far. Also, a device generally has to be 'paired' with the computer before it can access resources via Bluetooth, and that involves entering a matching password both on the computer and the device.
However, there are a number of possibly related Bluetooth security issues at play. An InfoWorld article published earlier this month describes "bluejacking."
"'bluejacking,' an increasingly popular means of exchanging short three- or four-word messages in the display area designated for the name of the initiating device [...] The process, essentially, allows communication to take place without pairing, which requires partners to exchange a PIN (personal identification number) to establish a connection."