sithramir said:
Just because a magical creature has darkvision has no reason for you to imply a creature that is merely "treated as " a magical creature should get it. Its treated that way because of the magical bonus's like speak with master and spell resistance and improved evasion that is granted by being the wizards familiar. Since they don't say it gains darkvision for being a familiar theres no reason to assume that it should just because a typical magical creature does.
Magical
beast. If you don't understand the difference the rest of this won't make much sense to you.
You failed to mention the only reason they actually are magical beasts. An animal companion gets everything you mentioned but is still an animal. Familiars are magical beasts because they have an intelligence of greater than 2.
Nothing more intelligent than that can be an animal. Familiars are more than just 'treated as' magical beasts, they are magical beasts because they can't be animals by virtue of the definition of animal.
That's right, low level type changing spell? Fox's Cunning.
Since they are magical beasts, by what's written they get darkvision because nowhere says that don't. The magical beast entry says unless 'otherwise noted' they get darkvision, no such note exists for familiars.
That is why, by the letter of the rules, familiars have darkvision. I'm not certain they should have it, but I don't mind terribly if they do. Regardless, it has a firm basis in the written rules, so I don't treat people who claim it to be true as insane little cheese-weasels. As DM it'd depend on how highly I valued Darkvision for the campaign in question.
SRD:
Magical Beast Type: Magical beasts are similar to animals but can have Intelligence scores higher than 2. Magical beasts usually have supernatural or extraordinary abilities, but sometimes are merely bizarre in appearance or habits.
Features: A magical beast has the following features.
--10-sided Hit Dice.
--Base attack bonus equal to total Hit Dice (as fighter).
--Good Fortitude and Reflex saves.
--Skill points equal to (2 + Int modifier, minimum 1) per Hit Die, with quadruple skill points for the first Hit Die.
Traits: A magical beast possesses the following traits (unless otherwise noted in a creature's entry).
--Darkvision out to 60 feet and low-light vision.
--Proficient with its natural weapons only.
--Proficient with no armor.
--Magical beasts eat, sleep, and breathe.
EDIT: Curse you and your brief replies, Trollman!