I've checked my iTunes folder on my Windows computer. There's ...iTunes\Mobile Applications\ which contains all apps' *.ipa files. I took a peek into one of them (i.e. added .zip extension and opened in Total Commander ;) ), but wasn't able to find any "content files" there (e.g. no PDF or RTF files in GoodReader), just the app. So when I synchronize or backup apps from my iPad to my desktop computer, where does the content go?