xhonzi said:

Yoda is not a warrior, he is a trainer. That's why he's not involved in the clone wars.

The real problem is that when we all saw ANH and the first half of ESB- the only "jedi" we'd seen were adult male human warriors. (Ben, Luke and Vader). The idea that this little smurf could be not only a jedi, but a powerful jedi held in reserve by the most powerful jedi hitherto seen was not even considered. We didn't say, "Oh, I bet that guy is Yoda" because How Could He Be?

Assuming there are more than a few jedi in your new PT, and assuming that they are not all adult male warriors... The possibilty that someone would guess that Yoda was Yoda is much higher even though Yoda is never seen nor heard (but possibly talked up) in your new PT.

To be clear: I am on the "Talk up Yoda, Don't show Yoda" team all the way. It's easily done, in my opinion. However, the other restictions required to really maintain the surprise are much more burdensome and you must ask yourself how committed to the surprise you are.

For the record: I am for preserving all surprises. Not because there is an audience in the world that would be fooled by them today... but because not doing so seems like cheating and poor storytelling.

My prequel notions are now headed in the direction of a meeting with Yoda. Yoda could suddenly appear as a harmless little creature and vex and annoy the Jedi candidates just as he did with Luke.

The thing about that is, it would leave us with a Yoda surprise if we watch Hope and Empire first, while knowing the gag in the preqs- OR we would have a Yoda surprise in the prequels if watched first and then know the gag in Empire.