Try emailing security@arisia.org and/or operations@arisia.org. They hold onto the items after con and then try to sort them out and get a list together within the next week or so that gets publicized. It may take them a day or so to get back to you, though...the people involved are probably exhausted and planning on catching up on sleep as well as helping move everything out of the hotel after the con.

I do recommend checking with the hotel as well, though. Some items that aren't obviously fan related end up in their hands.

Good luck!