Jedinet has a possible spoiler from someone at Fox Studios Australia. "Apparently the Republic has some new fighters in their arsenal, and it seems that Lucas might Spoilers - Highlight to read: be bringing the familiar X-Wing back into action in Episode III."

"The X-Wing is hidden behind a fence, which has a white plastic stretched across it. The X-Wing itself is just sitting amongst some other junk behind the fence. You can peek through a gap and see it clearly. The fence is on the far side of the public grass area (oval) at Fox, opposite the Hoyts cinema. Locals will have no trouble finding it! There is currently an amusement park set up on the oval."

Now, to see this new fighter in action would definitely be cool, but I believe it would be hard to introduce, because they were supposedly fairly new ships in the Original Trilogy which is many years after Episode III. There are other fighters that would make a lot more sense due to the time frame. Possibly the Y-Wing would be good because it was considered to be old in the Original Trilogy. Perhaps the introduction of Spoilers - Highlight to read: the Z-95 Headhunter would be appropriate because it was the predecessor to the X-Wing. Maybe that is really what the spy is seeing through the fence at Fox Studios Australia! The Z-95 Headhunter is very similar to an X-Wing and could be mistaken. I guess we will learn more soon!