UPDATE: Looks like MacWorld is on the case. They may have solutions for those who have already been stricken
Surprise! It turns out that there is automatic syncing between Macs and iCloud after all! It happens in the Mobile Documents folder. However, this is not a folder that Apple intends for end-user access. So be careful when meddling here. It is of limited value in any case. You may note that documents in this folder appear as folders, not actual documents. To convert one of these folders to an iWork document, remove the “-tef” from the extension in its name. Do this with a copy, moved elsewhere, not the original. Even if you do this, the document will not open in the Mac versions of iWork documents. It remains in an iOS-only format.
Beware...............
The cutting edge of technology is bloodying some folks again.
A heads up for Apple iDevice users trying out iCloud.................
Looks like syncing works on everything but iWork.
Irony.
Users reporting iWork documents being deleted via iCloud
updated 06:55 pm EDT, Thu October 20, 2011
Bug puts mobile iWork users at high risk of loss
Reports are coming into Apple's support forums that a serious bug in the way iCloud syncing is handling iWork documents -- those created by Pages, Numbers or Keynote -- is causing the files to be deleted upon a fresh sync, leaving mobile iWork app users in particular with lost documents and no apparent way to get the work back (Mac users can recover the documents via their Time Machine or other backup devices).
The effect has not been seen on other types of iCloud syncing, just iWork documents that are synced to iCloud from or to mobile devices. Although the issue is still being tracked down by users comparing notes on Apple's support forums, the problem appears to be that iWork documents are being moved automatically into a auto-delete folder when they shouldn't be. Some desktop users have reported recovering their work from the folder, which is found in the hidden (in Lion) user Library under the name "Mobile Documents" and/or "Mobile Documents.delete.(date)".
There is a video at the link, if you have doubts.
For mobile iWork users, the problem is much worse, as iCloud syncing is the main way users expect their work to be backed up. During the iCloud sync, all copies of the file on all computers or devices that have been synced are deleted, according to reports. It's unclear if this problem is affecting all iWork users who have upgraded to iOS 5 and turned on iCloud syncing for iWork documents or just a small group, but it has spawned several threads, each with a dozen or more users.
Some more evidence