I'm not sure "sync" is the right word but you can take desktop Statbook
created plist files (see the iPhone tab, "Save..." button) and then copy
this file to the iPhone app using iTunes.
To get the data from the iPhone back into the desktop Statbook application, this can be done via email ("Share" tab). Once you download the plist attachment, simply use the "Load File" button from within the desktop Statbook application.
It's more of a manual sync at this point. There are more specific steps in the Help area of the iPhone App if you need more information.