Wireless vulnerability
This was coming, but the the WPA wireless security protocol has now been effectively hacked. A Japanese group have developed a hack for the WPA protocol and will be presenting their findings in Hiroshima on Sept 25th (http://www.ieice.org/ken/paper/20090925faPH/eng/).
Here's the link to their full report:
If you are using WEP or WPA, I would strongly encourage you to switch to the WPA2 protocol as soon as possible. If you are using WPA with AES, you should be fine, for now. This hack currently affects WPA using TKIP. But if you have to switch things up might as well go to WPA2 with its newer version of AES. It's only a matter of time before this exploit is actively used, so time is critical.
Here's also a report on this from Network World:
http://www.networkworld.com/news/2009/082709-new-attack-cracks-common-wi-fi.html