I saw that katie compton has a custom aluminum frame from Trek which leads me to the question: Are the UCI bike requirement for cross the same as road as far as availability to the public?
I know that for road bikes they must be available to the public for purchase, but in cross I see a lot of frames including some disc models, that only the pros can get.
Since I can't check the UCI rules at work, a quick review of 'cross bike reviews, as well as my recollections indicate enough bike makers had disc-ready frames last season. Although I doubt a $15,000 Pinarello 'cross bike is "available" to the general public, the UCI doesn't have any rules about affordability, outside some equipment restrictions for Juniors. If enough US riders(on custom disc bikes) hit the podium in Louisville, the UCI might introduce some rule changes....
I'm under the assumption that Trek got the Ion CX UCI certified, and since the bike is simply a variation of that, it passes the smell test.
We outline the requirements for certification here: http://www.cxmagazine.com/ucis-new-bicycle-frame-approval-protocol-... if you want some light reading :-D