Bluesnarfing, according to Wikipedia, is the, "theft of information from a wireless device through a Bluetooth connection". Bluesnarfers will access files - including calendars, contacts, emails and more, on victim phones or computers, and 'snarf' (steal) these.
Apple recommends all users install Security Update 2005-005, which protects Macs from unwanted 'Bluesnarfing', changing an existing system setting which meant that Bluetooth-capable Macs shipped with Bluetooth file exchange services enabled by default. This meant files to be shared without properly notifying the user - a bluesnarfing vulnerability.
"Security Update 2005-005 disables Bluetooth file exchange and changes the location of the default transfer directory on systems where the old default directory is set. In addition, new users of a system must now enable Bluetooth file exchange before it is allowed.
The update also includes the following components: Apache, AppKit, AppleScript, Bluetooth, Finder, Foundation, Help Viewer, lukemftpd, sudo, Terminal, VPN, and X11.
A detailed account of the contents of this release is available here.