Massachusetts did put a revision in the 2002 MEC 210.12(C) that read:
(C)Overcurrent Device Replacements.
Where panelboards are replaced that contain one or more circuits requiring AFCI protection by this or other sections of the Code, AFCI protection shall be provided for such circuits.
This revision was quickly removed and did not make it into the 2005 MEC. Although it may be around for the 2008 cycle if manufacturers can produce products that satisfy the AFCI requirements under all circuiting arrangements.