Salts make cracking a list of N password hashes take roughly N times as long, but if a password is cracked anyway (because it's common and/or because the hash is not using very many rounds, or because an attacker only cares about one particular account), and the password is reused elsewhere, the fact that it was salted doesn't matter anymore.

GP is right; if owners of the leaked accounts [email, hash] pairs are reusing passwords, the leaked hashes are potentially useful even though scribd has reset them. They're simply not useful for logging in to scribd.

yeah if you simply know what a password is, of course it's compromised, but you're not supposed to easily break a salted hashed password.

Salts only really protect against rainbow tables; if the attacker is willing to use a dictionary or brute force attack against a single password, they're not of much use.