Yes, it'll be supported by Windows 8.
Win8 has no real support differences from Win7, so you're fine.
Razer is just too lazy to update their site.
Besides, I own a Razer Naga (blue led backlight) and it's just a simple mouse driver like any other mouse. The keypad is just sync'd with my keyboard so it's nothing special. It just takes more power than usual because of it's LED backlight.