updated 02:55 pm EST, Thu February 19, 2009
iWork file compatibility
Apple has acknowledged file compatibility issues with the new iWork '09 software suite that was debuted at the Macworld Expo early in January. Users running iWork '08 will not be able to open files saved in the iWork '09 formats. The issue also applies to Numbers '08, Keynote '08 and Pages '08 documents that are opened and saved using iWork '09.
The company suggests that users save files as iWork '08 documents from within iWork '09. The software will provide a prompt if the file was made with an earlier version. A copy of the file can then be saved as an iWork '08 or Microsoft Office document.
Apple has not yet announced additional details, including the possibility that future software updates will alleviate the problem.