GL reveals that Emperor Palpatine IS Darth Sidious!
In one of the interviews on TPM DVD, GL talks about Darth Sdious being a hologram in all the scenes, except one. Then he says this was the way he was introduced in ESB. Ah-Ha! Most of us figured that out a long time ago. So now it's official that Darth Sidious IS Palpatine (except it hasn't been revealed 'officially' in the movie storyline). I wonder why GL waited so long to tell us in a interview.
Who couldn't figure out that they were the same? They look pretty much the same. And there's Emporer Palpatine in the original three and then there's a Palpatine in TPM that looks just like Sidious who is the future Emporer. It's way too easy to comprehend.
Emperor Palpatine was not in the first movie (Episode IV). Grand Moff Whiluf Tarkin mentioned the Emperor several times, but that was it. The Emperor's original name was Cos Dashit (in the earlier scripts).