On my Mac I found two folders in ~/Library:
Mobile Documents
Mobile Documents.delete.Sat Oct 15 09:01:32 2011
each contains directories for the iWorks applications and in each a Documents folder. In "Mobile Documents" each Documents folder is empty. All my latest documents synced from iCloud are still in "Mobile Documents.delete.Sat Oct 15 09:01:32 2011". However, so far I have found no way to make iCloud resync the documents from the delete folder.
I can copy a document into the appropriate application Documents folder and shortly afterwards it shows up in iCloud and on my iPad. E.g. copy a Excel document into Library/Mobile Documents/com~apple~Numbers/Documents and it shows up.
However, this does not seem to work with the documents synced from my iPad to iCloud which are now in the "Mobile Documents.delete.Sat Oct 15 09:01:32 2011" folder. It doesn't seem to sync them back into the cloud.
So right now, at least I have a almost up-to-date version of my documents saved on my Mac but no way to get it back into the cloud...