indeed. and if this effect would be applied to nebulas ( Mutara, hint hint ;) ), it would create some interesting gaming situations.. 
I believe that the sensor jamming effect is already applied to nebulae in BC. My very first addition to BCFiles was the Nebula-Generating Weapon, and I seem to remember that when you create a nebula, there's a property which sets by how much the sensor range of a ship passing through it is reduced. Also, the wide-view map (the 'm' key) is rendered inoperable while near or inside a nebula.
# MetaNebula_Create params are:
# r, g, b : (floats [0.0 , 1.0])
# visibility distance inside the nebula (float in world units)
# sensor density of nebula(value to scale sensor range by)
# name of internal texture (needs alpha)
# name of external texture (no need for alpha)
pNebula = App.MetaNebula_Create(155.0 / 255.0, 90.0 / 255.0, 185.0 / 255.0, 145.0, 10.5, "data/Backgrounds/nebulaoverlay.tga", "data/Backgrounds/nebulaexternal.tga")
On the original topic, I can see two ways of going about creating a sensor jammer: The first would be to create a script which would disable or destory the Sensors subsystem of any ships in a certain range - and somehow restore the system once the jammer effect ends. Or second, find a way of isolating the sensor blinding effects of the nebula and apply it to the jamming ship through a subsystem property (like Slipstream Drive, in a way).
