In this InfoWorld article, researchers have disclosed that they were able to breach a laptop through a buggy wireless card driver.

“You don’t have to necessarily be connected for these device driver flaws to come into play,” [Jon] Ellch [a student at the U.S. Naval postgraduate school in Monterey, California] said. “Just because your wireless card is on and looking for a network could be enough.”

Personally I’m surprised this hasn’t happened earlier. Gives you a good reason to leave that wireless radio turned off when you don’t need it.