No this is not some kind of rollup fix pack release, SP2c to Resolve Shortage of Windows XP Product Keys [8-|]
Windows XP Professional with Service Pack 2c has released to manufacturing and will be available to system builders in September 2007.
Due to the longevity of Windows XP Professional, it has become necessary to produce more product keys for system builders in order to support the continued availability of Windows XP Professional through the scheduled system builder channel end-of-life (EOL) date of January 31, 2009.
There are no other features or fixes included in this service pack; it will only allow for the inclusion of additional product keys.
Source : Bink.nu