I rode the Starlight from OKJ to LAX in late December, and they had Wi-Fi enabled in the Pacific Parlour Car. It worked fine for the most part, and it was a very nice surprise to have Wi-Fi at all (I was definitely not expecting it).

Amtrak also now has Wi-Fi on the Pacific Surfliner (Business Class) now, as advertised by a shiny new advert from the Amtrak.com site (http://www.amtrak.com/servlet/Conten.../1237405732511)