It's a colour mutation of the Common Brushtail Possum and usually (always?) occurs in the Tasmanian subspecies. It is usually signed in zoos as Trichosurus vulpecula fuliginosus var. golden.
Worth noting that the Golden Brushtail Possum (pictured above) is different to the Coppery Brushtail Possum (Trichosurus johnstonii) from the Atherton Tablelands in Far North Queensland. See the Australia Wildlife Gallery for pictures of those.
It certainly is quite striking though, and seems to be more common in Australian zoos than the normal colour of the Common Brushtail?
It may have appeared that way to you, but the normal colour is far more common. I think I've only ever seen a couple of goldens, but plenty of normals.
It may have appeared that way to you, but the normal colour is far more common. I think I've only ever seen a couple of goldens, but plenty of normals.