Actually, now that I look for it, it isn't there anymore... It used to be in the main directory in minecraft.jar, right next the the normal char.png. I've looked through the whole archive and I can't find it, it must have been removed in a recent update.
Private Mod Note
Rollback Post to RevisionRollBack
Minecraft is the meth of video games, try it once and you're hooked, and you'll stay up for 3 days when you're on it.
no skin can be even one tiny bit transparent if one part is left transparent it is tuned to black once you join a game, this is to prevent invisible players from being able to sneak up on someone in pvp and kill them,much like the xbox and the invisible option when the invisible option on xbox is selected you canot hurt anyone but you are invincible.