これは、ドメインがjsbinにクロスドメイン要求を明示的に許可するためです。
Request URL:http://opensocial.flixster.com/igoogle/showtimes?date=20111027&postal=23226
Request Method:GET
Status Code:200 OK
Response Headers
Access-Control-Allow-Credentials:true
Access-Control-Allow-Origin:http://jsbin.com
It is documented here https://developer.mozilla.org/En/HTTP_access_control