As quite a few people have mentioned, in Australia we all owe an enormous debt to Dr Arthur Pape and his successes at the AAT in the '80s. Even today, these cases are still viewed as the most exhaustive and comprehensive examination of the aviation colour perception standard that has ever been conducted - with the overwhelming conclusion of the tribunal being that colour vision defectives do not pose a risk to the safety of air navigation. Do a google search for 'Colour Vision Defective Pilots Association' which he has recently formed and you will be enlightened.
For those with CVD that have aviation careers in Australia and got there by virtue of passing the tower signal gun test - you have Arthur to thank for that. Previously we wern't even able to fly at night before these successful appeals cases. Having said that, there are still lots more CVD's that still need support though (both here in Australia and internationally) and Arthur's now in the process of coordinating further legal challenges to rid the discrimination once and for all. If you have any interest, I'd highly recommend getting in touch with him.