I am running a Mountain Lion server at home on a Mac Pro (2008). All seems to be going well with the exception of the following: users are unable to access their documents stored in iCloud through apps like TextEdit, Pages, Numbers, etc. While "Documents & Data" is enabled on the accounts, and all other iCloud account services seem to function properly, accessing iCloud documents brings up an alert sound and the folder path to their network home folder's documents folder. Interestingly, logging in to the network accounts locally (on the server) does not create this error.
I have tried signing in and out of iCloud, as well as testing the error on different accounts
I have now tested with Mavericks Server and Mavericks client, and "Documents & Data" is currently simply greyed out - which is, I suppose, an improvement over leaving it available but not functioning. Another discussion thread on this in the community (https://discussions.apple.com/message/23477544#23477544) seems to indicate that Apple simply does not support this feature for network accounts, although it will work for mobile accounts (which I have not tested). I wish I could have those hours of trying back. Sigh.