The patent trolls are already on it, patenting crowd-sourcing as a method of patent defense. This will inevitably result in the shut down of Ask Patents in a stunning fit of irony.
How about patenting the method of submitting a document to register a patent?
Unlikely. After all you have an entire site dedicated to finding prior art. I wouldn't want to get my patent killed over that.
If only some sort of prior art could be found...
Unless SO itself gets issued said patent, and then turns around and issues a royalty-free worldwide license on it to everybody.