I just purchased a brand new iMac running 10.8.3. A few days ago the issue started with iPhoto...no dragging to desktop from the application. I've tried numerous things including running the built in iPhoto repair and rebuild utilities and the Library Manager app and re-creating the library but the problem persisted.
I read another post where a user suggested wiping out the preferences file under Library>Preferences and restarting....I tried this and it worked. Drag and drop from iPhoto and iTunes is back.
Now, I think it's a pretty nuclear fix...I've had to setup some things again like my iCloud account preferences after reboot......bit it did fix theproblem.
Maybe this will help those that the other fixes are working for...