Ok the part about "found in a long lost temple" i made up, but there has been a real Master Sword forged.
Found in a news article on Planet GameCube by C-E fourm member "well_chuffed".

A member of the Planet GameCube fourms paid �1,800 to Scottish blacksmith Rob Miller of Castle Keep to forge a replica of the evil destroying, blue glowing sword of Hyrule Legends.

Pictures of the sword can found in the PGC news article Here. Oh and for those (like me) who might think "Shouldn't the hilt be blue?", this replica is based on the Master Sword from A Link to the Past and is a perfect replica of that version of the great blade.

Like many others out there I know i would love to have one of those. Better start saving those coins so.