I just experienced a nice Bug that took me some time to figure out.
I had a Mongoid Document with a Workflow included. I had a state new, which created a method called "new?", checking, if the state was set to 'new'. So when Mongoid checked for new? it got the information, the state was new, and created a new document.
So it would be nice, to rename the method to new_document? or new_record? like ActiveRecord does.
i can start doing this, if you guys are OK with this.