I'm not sure all pediatricians are as comfortable with and positive about GTness (let alone homeschooling!) as mine is. But if they were, I'd support your idea, kimck. Pediatricians probably interact with more different kids on a daily basis than just about anyone else. (Even teachers only see the same 25 kids every day for a year!) If any non-GT-expert might have the breadth of experience to spot a potentially GT kid in minutes, it's probably a ped!
In an ideal world, a pediatrician would have this kind of background and information before leaving medical school. It conceivable that many docs would be at least MG, but it's also conceivable that many would have never been identified as such (like myself!). It seems like it should addressed right along side with identifying possible autistic tendencies, speech delays, growth problems, etc. IMHO.
In my same dream world, teachers would also have this information in their arsenal before getting a teaching license. Ah ... it's fun to dream!
