Wireless network security weakness to demo at DEFCON:

Security researchers have discovered security shortcomings in the WPA2 protocol that threaten the security of wireless networks, even if they are running up-to-date security software.

The hack involves generating arbitrary broadcast packets from a spoofed node that trick legitimate nodes in a targeted network into responding with queries that give away information about their secret keys. The traffic does not, of course, give away the private key directly, but it does provide enough clues for this information to be extracted by subsequent cryptanalysis and high-end number crunching.

In order to exploit this flaw, a user needs to be authorized, BTW.