yes and no, this is more of a login page so I suppose the brand isn't as important.
Having said that I don't like some of the 'brighter' colours like the pink and the blue because you lose the white text.
I think that as long as the logo and the overall design is very recognizible the color might not be indispensable. The first example that comes to my mind is FedEx, which shows a consistent logo but different colors depending on the service offered.
I agree that colour can be very important for the brand. My idea for this was that the colour of the brand would be white, and the background would simply be environmental, changing each time to keep things interesting like the Bing start screen.
Tony, you are correct in saying that the pilot colour was blue of rgb cyan, which was probably my favorite.