I got this from the Apple Support:
UPDATED : The website now clarifies the feature as 'coming soon'! MMe support say they have NO IDEA.
My name is Mike from the MobileMe Support team and thank you for your inquiry about iDisk File Sharing. This feature is not currently available with MobileMe.
When MobileMe was announced, iDisk File Sharing was mentioned as a feature; however, the MobileMe webpage noted that all features listed on that page were subject to change. When MobileMe was released on July 10, 2008, iDisk File Sharing was not included. I apologize for any inconvenience.
However, you can certainly use the Public folder of your iDisk to share files. You can access your Public folder through the new MobileMe interface. The new Internet address (URL) for iDisk Public folders is this:
http://idisk.mac.com/membername-Public
For more information about sharing your files using iDisk, please review this article:
Using your iDisk to share files
http://support.apple.com/kb/HT1774
Thank you for allowing me the opportunity to assist you. You may receive an AppleCare survey email; any feedback you provide would be greatly appreciated.
Have a wonderful day!
Sincerely,
Mike
MobileMe Support
UPDATED : The website now clarifies the feature as 'coming soon'! MMe support say they have NO IDEA.