SimpleDB is indeed still up and running. Considering how it was described from the start as "retail store product catalogue" I wouldn't be surprised if AWS is

SimpleDB is indeed still up and running. Considering how it was described from the start as "retail store product catalogue" I wouldn't be surprised if AWS is keeping it around due to demand from a single large customer which starts with "A" and ends with "Retail". I wouldn't be surprised if SimpleDB has been reimplemented on top of DynamoDB though.