Your password must be at least 18,770 characters and cannot repeat any of your previous 30,689 passwords. Please type a different password. Type a password that meets these requirements in both text boxes. Note that the number of required characters changes from 17,145 to 18,770 with the installation of SP1.

You're telling me that it shouldn't be 18,291? Because I could have sworn it was when I looked the other day. Now, before you start freaking out, Microsoft can send you the fix – but only if you're impacted by this (obvious) oversight. Again, I can't stress this STRONGLY enough: you should only ask for the fix if you're seeing numbers like 16,322, 29,192, or 21,299. I wouldn't recommend setting a password less than 18,770 characters, regardless.