What will we see of Sauron?

Will he be featured much in the final film?

It looks like he will be. in an interview Jackson said that you couldnt film starwars without ever seeing Darth Vader, plus in a couple of other threads some people have actually found a lot of info on it.

Yes, rumour has it that Suaron actually achieves physical form again in the films.

EXCITING!!! I think he is even supposed to be at the black gate. a deviation i dont mind.

Nor do I. You might want to put that in spoilers though, just so the non-spoilerific folks don't read it...

Unless Peter Jackson makes some really overt changes to the ending of the story, Sauron does not appear in bodily form. There is a shadow of a hand but that is all. He has not gathered strength enough to take on physical form and that is one reason why he wanted to get that ring so badly.

There are going to be changes. This could be just one of many.