Joe,
Yes they can be curved. I have a couple and if you are patient you can curve them real well actually. I like that they start flat though, b/c the way my head is it is harder for me to wear my shades with a curved bill...
Oh, and I was at Aggieland Outfitters last week and this is an Adidas hat that looks just like the baseball one but with a curved bill (T-Star on back). To be honest, all of the work on it is to the same scale as the flat bill. It is flex fit and the s/m were a little snug on me (I normally wear a 7 1/4 hat size) if that helps...
http://aggielandoutfitters.com/mens/hats/structured-flex-2011[This message has been edited by Capitol Ag (edited 3/22/2011 10:37p).]