Do PDF documents in iBooks get backed up to iCloud? Do PDF documents in iBooks get backed up to iCloud?

It is very strange that there is no answer to this on official Apple forums. Searching for this online often brings up Wifi iTunes sync or using file sharing services like box.net to do this.
Yes, as long as you have the iCloud backup enabled your documents will be backed up. I have first hand experience. After exchanging a defective iPad the new one, after entering my iCloud account information, had all my books (both epub and pdfs, I don't buy books from the iTunes store because of DRM), links, gamecenter data, and application data.

What didn't synchronise was music and videos.