Star Wars: The Old Republic Preview

There's an informative three-page preview of Star Wars: The Old Republic up at GamesRadar, during which lead designer James Ohlen shares his thoughts on various aspects of the MMORPG.
As in Mass Effect 2, your companion characters will have their own personal stories and quests that get you mixed up in them. And because they're unique to your class, these can also tie in to your own storyline. The downside of this system is the same reason it's not normally done in multiplayer games: you're going to see other people running around with the same friend as you. (To take your Chewbacca example,) Olhen says, (if you run into a Smuggler, and he's adventuring with his wookiee Chewbacca, yes, the stories of the two companion people will be the same, they'll be doing the same interjections in your conversations.)

This, you will notice, is silly. (It was one of our concerns early on in design,) Olhen admits. (But you're not going to have identical companion characters. We're thinking of ways to make sure you can customise them so you don't get confused, so you don't get the Chewbaccas mixed up.)

When playing with friends of different classes, at least, it's going to be fun jetting around the galaxy with your chosen AI pals. They'll round out your team's abilities and have things to contribute during conversations with NPCs. Since your real friends will also pipe up in these exchanges, they'll start to feel more like scenes from films than the usual interview-like format of game dialogue.