The only thing I've seen mentioned is a t-shirt offered in a men's and women's version. There was an opening day pin but those were sold only on opening day. I hope there's more by now! What happened to them selling copies of the artwork?
Here is a photo of the Bay Lake Tower t-shirt being sold in the Fantasia Market store on the 4th floor of the Contemporary, which I purchased for myself when I was there last month.
Besides that on their opening day there was a grand opening limited edition pin which one of my friends got me since he is a DVC member, however he also said it sold out that same day. So if you want one the best place to find one is on Ebay and here is a picture of what it looks like.