iDisk is not the best user experience Apple has to offer and I hope that they are going to realize that in the near future. One of it's many flaws is the lack of a simple way to get the public URL for a file (without opening the web interface), preferably from the Finder.
This is a script for Automator. Create a new service and select "Service receives selected Files or folders in Finder". Add the "Run shell script" action from the library and insert the code from convert_path_to_idisk_url.rb. Save as "Copy public URL".
Open Finder, select a file, go to Finder ➞ Services ➞ Copy as public URL.
You have to wait for the script to execute, it can take a second or two. There is no feedback when the script is done.
I recommend adding a keyboard shortcut via System Preferences ➞ Keyboard Preference Pane. Mine is ⌃ + ⌘ + C.
