Is Sasuke on the good side or the bad side? Good question. People will be asking this for at least a few chapters to come. Personally, I find him neutral right now, but if he goes either good or bad from here, I'd imagine he'd turn good. Yes, like Memoria said before me, his teaming up with Itachi doesn't mean he is absolutely, positively on the good side; he's only on his brother's side. I think, however, Sasuke is slowly turning his back to Tobi, Kabuto, and their bad guy side of the war. He'll fight with Itachi now, as an ally, and we'll have to see what happens to said beloved big brother of his before we really go making a decision as to which side he's on. And that'll, surely, be in many more chapters to come; this battle will take some time.
But, on a side note, if you look at the cover page for Chapter 578 you'll see that, in the three panels, Kishi placed all the heroes/good guys on the left and the villains on the right, grouping the characters, horizontally, by the fight they're taking part in, but vertically, it would seem, by what side they're on, if only technically, in the war right now. Sasuke is standing beside Itachi, yes because they teamed up, but I think Kishi places the heroes and villains on the same side in each panel to possibly foreshadow Sasuke's transforming heart. I hope that makes sense. It's how I've come to look at it, although we all have plenty of time to think it over.