You know the Predators were (and possibly still are) transmitting all their video without any encryption?[1] And they've also suffered virus infection on their ground-station computers?[2]

I don't know whats running on the actual drones, but it wouldn't surprise me at all to find there's well known exploits against something like QNX or VxWorks (or, and I shudder at this thought, Windows CE) that the drones are vulnerable to whilst in-flight…

[1]http://arstechnica.com/tech-policy/2009/12/predator-drones-u... [2] http://nakedsecurity.sophos.com/2011/10/10/malware-compromis...