If you thought that was a honkin' big coincidence, wait'll you get a load of this 'un...
Those same sharp lads at GeekTyrant have scored another find. The whole plot of Inception is eerily similar to Dream of a Lifetime: a 2004 Disney-published comic book about... Scrooge McDuck!
Here's a page from the comic. Click on it to drastically embiggenize...
According to the guys at GeekTyrant, Dream of a Lifetime "... tells the story of how the Beagle Boys used a device to enter Scrooge McDuck's dreams to extract the secret combination to Scrooge McDuck's vault! I dead freakin' serious! Did Nolan get his idea from a Uncle Scrooge comic book!?"
Mash down here for the link to GeekTyrant's page, which has a link to where you can read the comic in full.
Yah, that's a great find. However the more I think about it, the more examples of this same "invading a person's dreams" thing I'm able to think back upon. There was an episode of Batman: The Animated Series involving Mad Hatter that was kinda like this. And I even remember one of the episodes of G.I. Joe: A Real American Hero years ago that had Cobra's Dr. Mindbender messin' with the Joes' dreams (one of the Joes, I think it was Low-Light, turned the tables on Cobra 'cuz he didn't sleep normally, or something...). However nothing that comes to mind bears anything as close a resemblance to how dream-stealing worked in Inception than does this Scrooge McDuck comic.
Now all we need for the world to be perfect is to wait for Muppet Inception.