The Hershey's lawyers have denied Cafe Press permission to pass along the Cease and Desist letter to me, citing concerns (and rightfully so) that we would post it on the website, making matters worse. Of course, that means that we have not directly been served with a Cease and Desist letter, so we may technically still be able to sell the shirts in one form or another (although, this is highly unlikely). Again, I'm looking into my options.
I spoke with the Executive Director at the Comic Book Legal Defense Fund today. He was very helpful, and compared our case to that of the Starbucks Logo Parody created by Kieron Dwyer some time back. The parody itself was allowed, but not the merchandising of it, so we may be in a similar situation. There are some subtle differences at work here that lead me to believe that we still may have a case, however. I'm going to continue to pursue the issue, and will let you know when we have more information.