Although much hasn’t changed with the iDisk after the switch from .Mac to MobileMe, I have noticed a couple welcome changes:
First, when uploading something to an iDisk, you get a real progress bar/file transfer box.
In the past, you would probably just see this box for a few seconds. It would close quickly, looking like the upload was completed, but the file would still be uploading to the iDisk in the background. The only way to tell the upload was completed was by checking the file size on the iDisk.
The second welcome change to the iDisk involves iDisk syncing. In the past, iDisk syncing was completely secretive with no way to tell when or what was being synced to/from the iDisk and your computer. Now, when your iDisk is syncing, you get a handy display in the bottom of your Finder window: