Non ASPX Extensions and Authentication in IIS 7 Integrated Pipeline

Ran into an issue where IIS 7's integrated pipeline exhibits different behavior authenticating non ASPX extensions. Looks like IIS 7 only authenticates mainline files resulting in Context.User==null or Context.User.Identity.IsAuthenticated==false on all other extensions. For example hitting CustomHit.axd doesn't provide user credentials where an CustomHit.aspx does.