Here's the reply I got when asking Jay specifically about using the box graphics for our web site:
Riogames@aol.com wrote:
> Actually, as long as you give proper credit (to Hans im Glück and Rio Grande Games
> and do not sell the images, you may use them freely.
>
> Good luck!!
>
> Thanks for your interest in Rio Grande Games.
>
> Jay Tummelson
> Rio Grande Games
>
www.riograndegames.com If you use
original graphics that are similar to the Carc graphics that's another thing. Plus, it's another thing entirely if you sell them. I would contact Jay at the address above, making it crystal clear what your intent is and what his opinion is, he's excellent at getting back to anyone.
There are legal ways to get around selling them as well (ie just sell the bag they come in, get the tiles free).