I can't imagine it's more than checking the brake system (maybe bench cycling the ABS), possibly bleeding and replacing pads. You could always call a dealer and ask the service dept what exactly is involved.
According to cars101, the US maintenance schedule doesn't really show anything to do with the brake system that would cost $400 unless they're automatically lumping you in to a "severe driving condition" rating and replacing a lot of stuff at the 15k or 30k mile service instead of a simple inspection.