Do every Android version store the PIN/passwords at the same file? I find a hateful peculiarity of Android its nagging usual changes between versions in the paths for some system files and configuration variables. Even when I assume it is expectable on newborn operating systems.  

I have read that the PIN number for unlocking the screen is stored (cyphered, I pressume) at /data/system/password.key .  So, for example, if I do:

# rm /data/system/password.key


... I will be able to delete it (of course priorly mounting the partition system as read/write, booting via Recovery, connecting via ADB shell, on a rooted device... blah blah blah).

Could this change work on every version of Android? Or this storage file is version-dependent?
According to this source 


  Android stores this pattern in a special file called password.key in /data/system/. As storing the pattern in plain text wouldn’t be very save, this time Android stores an salted SHA1-hashsum and MD5-hashsum of the PIN or password. The numeric PIN and the alphanumeric passwords are processed in the same way... 
  
  Due to the fact that the hash is salted this time, its unfeasible to crack the password with help of a dictionary attack. For cracking the password it is important to get the salt and enough time for attempting a brute force attack. The salt is a string of the hexadecimal representation of a random 64-bit integer.


From this page it seems you are correct in believing that the password is located here in at least the 2.2 versions of Android and later.