Facebook does something different. They accept two extra variants of the password (first letter capitalized and case reversed). They don't uppercase the password before hashing or checking. This reduces the security slightly as opposed to uppercasing passwords which reduces the search space significantly.

facebook does a different thing. It does not allow any casing(sp?). It allows only the right and the reverse and first letter in uppercase.

Blizzard seems to uppercase the given password and hashes that. This method makes a lot of wrong passwords work. In facebooks case only two more passwords than the original are accepted.