EDIT 2/18/08- FOUND THE SODA @ SUPER WAL-MART. I've only had one sip so I can't provide a proper review at this time!
Crystal and I have been looking for this new "limited edition" Cherry Chocolate Diet Dr. Pepper for the past month or so. No luck anywhere in the Worcester area. We have checked out Wal-Mart, Target, Shaw's and Price Chopper without any luck along with a few convenience stores.
There is a coupon for it in Rolling Stone every week and we have been stockpiling the coupons because we aren't able to find the soda. Crystal loves chocolate, I love tying out new sodas so it has been frustrating that we can't find this anywhere.
I just had the great idea that I would ask the local blog community if they have came across this soda in their local travels.