First, just to make sure I understand "salting" correctly:
You randomly generate a string to append to the password before hashing it, so as to increase its length and make precomputed tables much less useful in cracking them.
Assuming my understanding is correct, then I'm having trouble how LinkedIn salted their passwords:
One of our major initiatives was the transition from a password database system that hashed passwords [...] to a system that both hashed and salted the passwords [...] That transition was completed prior to news of the password theft breaking on Wednesday.
Doesn't salting require you to have the plaintext password? How can you salt a hashed password?