iWork 09, no backward compatibility...

I just downloaded the iWork '09 trial package. Reports on the net mention its enhanced Applescript support, its new looks and new functions.

Pages '09 opens Pages '08 files without difficulties and can save into that format (see the new Share menu), but the new format cannot be opened in Pages '08.

A Pages '08 was basically a folder with a .pages extention. You could go to Terminal and do a:

$ cd

to find the following list of files:

$ ls
Contents QuickLook index.xml.gz

where both Contents and Quicklook were folders with files in them, while the file itself was a gz-compressed XML file (index.xml.gz)

Now, the same file created by Pages '09 would have a totally different structure.

Where file_name.pages was a folder containing compressed data in Pages '08, the file is a compressed folder containing normal files.

To see what it looks like, change the .pages extension to .gz and double-click that file. The result is a folder with the following files:

$ ls
QuickLook buildVersionHistory.plist index.xml

Quicklook is still a folder with a PDF (Quicklook) and a JPEG (thumbnail) preview of the file but the old Contents folder is not there and the index.xml contains XML code that significantly differs from the one in Pages 08.

Keynote '09 and Numbers '09 show a similar internal structure for their files.