AbdulAlhazred
Legend
Of course in return they don't send you the "thanks, but you're done doing that now" letter. It does generally seem pretty fair. Some things like Mind Flayers are just VERY D&D. Honestly I think its good because it forces designers to invent new stuff instead of just rehashing Gary's Garage circa 1973.A complexity with using the OGL is that, as part of your contractual obligations, you agree not to use certain WotC text and ideas that potentially go beyond what would be protected via copyright and trademark law alone.
Do WotC have registered designs or patents for 4e elements?
Unknown. In theory I guess you could do a search, but I'm not sure how hard it is. The Design Patent is a weird beast.