Occasionally, when using one of the many great features included with MobileMe, users will encounter an error telling them their iDisk is full.
.Mac iDisk and file corruption
Losing iDisk Data (#2)
10.1 and iDisk mounting problems
When trying to access the MobileMe iDisk in the Finder, you may run into a problem where the disk will not mount and will give an error stating "Your iDisk is unavailable."
More on .Mac iDisk file corruption
There are a couple of URL schemes that will work for linking to files on the iDisk, making it easy for users to simply upload a file to a folder on their iDisk and then directly access that file by typing an address into a web browser or email client.
Apple has issued a small knowledgebase update on MobileMe "iDisk full" errors and related problems.
iDisk and Keychain: one more follow-up