The website has managed to discovered two devices which feature the model numbers GT-I880 and GT-I8805, although we’re guessing they are probably the same device, with the latter probably offering an additional feature such as dual SIM slots or LTE. Further digging by the site revealed this information: Mozilla/5.0 (Linux; U; Tizen 2.1; en-us; SAMSUNG GT-I8800) AppleWebKit/537.1 (KHTML, like Gecko) Version/2.1.0 Mobile, possibly confirming that these are indeed Tizen-based phones.
Samsung expects to debut Tizen devices later this year, so we guess until then, the GT-I8800 and GT-I8805 are possible Tizen models to look out for.