This is how I've been doing it, even before the mac.com -> me.com transition.

If you mount your iDisk on your desktop, there should be a Web folder at the top level. Inside that should be a Site (or Sites) folder. Open the Site folder and create a new folder inside there, maybe call it "images". (I call mine "dump" since I dump images there.)

Put pics you want to share in that folder, then you should be able link to them with a url like

http://web.me.com/thebukos/dump/2stone.jpg