From the Disney Parks Blog:

One of our goals for the new Star Tours show was to pack as much Star Wars into the attraction as possible. That meant traveling to different planets, and meeting up with classic characters from the saga.

Of course you already know that R2-D2 and C-3PO are back, reprising their roles in the pre-show, and taking on bigger roles (especially C-3PO) in our Starspeeder adventures. And some time ago, we introduced you to two new droids in our show…Star Tours Pilot Ace (AC-38) and Spokesbot Aly San San.
So who else is joining the cast?

Well, it wouldn’t be a Star Wars adventure without Darth Vader. The Dark Lord of the Sith will be accompanied by legions of stormtroopers and some new “skytroopers,” designed especially for our show. Boba Fett, everyone’s favorite bounty hunter, also will be after us, as well as an assortment of nasty droids and creatures.

Balancing out the villains are some classic good guys – and even a princess! Master Yoda, Admiral Ackbar (pictured above in a still image from Star Wars: Episode VI Return of the Jedi) and Princess Leia will appear in the show to help guide our adventures. We may even run into Chewbacca along the way!

From Disney Parks Blog:

It was a big day for Star Tours recently, as Star Wars creator George Lucas, joined by producer Rick McCallum, paid a visit to Disneyland Park to take a few test rides on the attraction with our Walt Disney Imagineering team. After experiencing adventures to several of the Star Wars worlds aboard the Starspeeder 1000, George and Rick gave the team a big thumbs up on their progress. George even took a moment to pose with the Audio-Animatronics figure of C-3PO in the Starspeeder cockpit!

Stay tuned for more Star Tours updates.