In theory, it just slows it down so rainbow tables are ineffective (not that people need them anymore), and it requires you to brute force each password than brute forcing one password and then checking it against everything.

In reality, it's all MD5 and the passwords were leaked to a community who are running tons of GPUs to brute force hashes. So it's kind of irrelevant.

You can recreate the hash by calling crypt() in php with your PW and the full hash as arguments. Basically, the hash is built like $1$_salt_$_hash_ - by feeding it as an argument to the function, you make it use the same salt used originally at encryption, when it was randomly generated. This is exactly the way these hashes are verified on login.

I'm not even much of a PHP fan, but it seems like you're unaware of what most people use. Including financial institutions.

Haha. I came from PHP and won't ever go back, but, you would be surprised what people use PHP for.

What would be the point of doing that?

You can also have real money in your mtgox account.