Heads-up on this one people (YASQ - yet another sharepoint quirk):
When having content approval enabled for a document library and using explorer view to make changes, content are not automatically approved when adding items or making changes. This can give the impression of stuff disappearing in your document libray.
If you've got content approval enabled and add or rename a file or folder in Explorer View it will simply disappear from the All Documents view. You'll have to approve the change in the Approve/Reject view to make it appear again. Very scary if you had a million documents in that folder.
To make the confusion complete you'll also need to be aware of possible caching in the Explorer View control. If you create a folder called "test" in Explorer View, then return to the Approve/Reject View and select "Delete" on the item pending and return to the "All Documents" view the "test" folder is gone. If you open the Explorer View again the folder "test" is still there (at least in my browser). Clicking the folder will give you an errormessage.
These things just gave me the chills, but fortunately it was less severe than first expected.