I'm wondering if it's not a mental thing, but a physiological thing that's making different people interpret the color in different ways.
For example, for me, it's so obviously more purple than blue that it's not even funny.
edit: oh yeah, look at my avatar, my sig, and the hair on the right side of my sig. that's blue(what the berk is not). look at the... oh, I see someone has edited the BG background to illuminate this contrast..