Interesting info on the DSC8+ system as fitted to petrol Range Rovers from 2006 onwards:

http://www.scribd.com/doc/47224437/Bosch-DSC8

I'd like to know if the RR does employ the "Dry Braking" system. i.e when the wipers are on it gently applies the brakes every 90 seconds to ensure the discs are dry. 

Is it really necessary? Without doing the maths a car travelling at 60 mph has the wheels spinning fairly quickly! The centrifugal force would remove any signs of dampness.

Does the 90 sec interval keep the disks warm, as opposed to dry?

One does have to wonder if it's a scam by the manufacturers to make sure you wear your pads out nice and fast.

Have you read the doc in its entirety? If you take your foot off the accelerator pedal quickly it holds the pads against the disc so the pad is ready to bite if you need to do an emergency stop etc...