Bruce Schneier links to this research just presented at 26C3. While quantum key distribution systems rely on unique, quantum mechanical properties of particles, the attack takes advantage of flaws at the same level. Some of the photo receptors used apparently are vulnerable in such a way as to allow an eavesdropper to completely sniff out a secret key distributed through a quantum channel.
It isn’t clear from the abstract whether this technique would be effective against the improvements on quantum key distribution that I talked about recently on the podcast. What is clear, a contention with which Schneier would seem to agree, is that if anything valuable is exchanged or stored under any type of encryption, then some attacker somewhere will be motivated enough to find a way to get at it. Sprinkling on quantum pixie dust doesn’t change that analysis.