Easterhay said:
They might not have released a 3D TPM on Blu-ray because 3D has turned out to be such a dead duck. Even Blu-ray hasn't been as much of a hit with the masses as DVD was.

Then why are the studios finally releasing 1950's classics like Dial "M" for Murder and Creature From the Black Lagoon in their original stereoscopic glory? It costs money to restore these things.

I would think they would hold off on TPM until the rest of the prequels have had their theatrical 3D runs.