Again, until ENDA passes, there's still de jure discrimination in hiring in a great many parts of the country, as you can literally give "you're gay" as a rationale for firing someone in a great many jurisdictions. It's the natural follow-up to gay marriage.
Why is most of the Northeast OK with gender discrimination while opposing sexual orientation discrimination?
Pretty much what Benj said. It's a function of when the laws were passed. Trans* issues were much less visible, say, ten years ago than five years ago.
