Hi there everyone!
I also lost all my iWork documents yesterday. I opened a case to apple regarding this but haven't heard from them yet.
I managed to salvage all but my Keynote files back to iCloud. I did the following steps from terminal:
1. I have copied the documents folder in "~/Library/Mobile Documents.delete.Wed Jan 4 09:19:53 2012/com~apple~Numbers" to "~/Library/Mobile Documents/com~apple~Numbers".
AGAIN: MAKE A COPY! Don't move the folder in case it doesn't work. Maybe even make a second copy fo the whole ".delete" folder to have a backup copy available!
2. I have renamed each document folder, removing the ending "-tef", e.g. renamed "My First Document.numbers-tef" to "My First Document.numbers". This makes the document appear in iCloud shortly afterwards. You can't open it as it is considered a document created by the Mac Numbers application.
if you have many documents using a short cmd line script is helpful;
# for i in *.numbers-tef; do mv "$i" "${i/.numbers-tef}".numbers; done
3. I have renamed each document folder back, i.e. "My First Document.numbers" to "My First Document.numbers-tef"
4. Now iCloud seems to sync it up again and recognizes it. It reappers on my iPad and I can open it.