After updating my devices to iOS 5, I went to sync my documents with iCloud. iWork documents successfully synced, and were viewable on my iPad, iPhone and iCloud. But this morning the Pages, Numbers, and Keynote docs disappeared from my iPad. No file on iCloud. All documents lost and no longer stored in my local backup. Restarting and restoring the iPad failed. That's a pretty serious bug.
* On your Mac, go to ~/Library/Mobile Documents.delete.*****, and copy the files to "~/Library/Mobile Documents/". For example, to recover my Pages documents, just copy "~/Library/Mobile Documents.delete.Sat Oct 18 08:00:20 2011/com~apple~Pages/Documents" to "~/Library/Mobile Documents/com~apple~Pages/Documents".
* Rename each document folder by removing the ending "-tef", and rename each folder back again.
* Then the iCloud will sync docs up again and recognize them.
That works and everything comes back on iCloud.com, iPad and iPhone.