USPS 2012 changes?

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Hi - last year when USPS changed their internals on Jan 2, 2011 - it knocked my website for a loop.  I needed to hire a developer to fix it.  I just received notice yesterday that they are changing things again come Jan 22, 2012.  The email claims "backward compatibility" - does anyone know this to be true?  If not - what do I need to do to insure the transition goes smoothly?  I know sometimes patches are released.  Thanks so much!