Hii..I'm facing another problem in unity and can't decide how to make an object from transparent to translucent to opaque when game is active. the transparency should change to opaque as my character comes near the object.
You need to alter the main color's alpha value on the material(s) involved. You could find the distance and then scale that to the 0 to 1.0 used by the alpha channel.
http://unity3d.com/support/documentation/ScriptReference/Material-color.html
Its funny, because I'm not actually googling anything...