I’ve been using Mobile Me since 2002. (Then it was called .Mac). One of the features I really like is the iDisk. This is really convenient when you have to transfer large files. Also, I use it to keep a set of files I need again and again for my work as an agile coach. To make the access transparent and fast you can keep a copy of your iDisk on the local Macintosh HD and use it like any other drive. There is a sync process running in the background taking care of the data syncing. Very nice and convenient. In the beginning I could put a symbolic link into the local iDisk to reference a folder with the files on my local hard drive. Then the files were synced onto the iDisk in the cloud and I could access them from anywhere.
However, with the release of Leopard this stopped working. Well, rather annoying but not a real big problem. I just created a folder which I kept up date manually. But, since the iPhone has an iDisk app I started to read and re-read certain documents while on public transport. As you can guess, it happened again and again, that I forgot to do the manual update and therefore could not read important documents.
rsync to the rescue. With rsync you can keep folders in sync. I use it to keep the folder on the iDisk an exact copy of the folder containing the documents.
Now at midnight, the documents are automatically synced from the local folder on my hard drive to my iDisk. There I can access them using my iPhone or my notebooks. (iDisk also has a Windows client).
If you run into the same problems, then hopefully this shed some light onto it.