First, congrats on matching. Welcome to the club! Radiology is a fantastic field with a bright future. Unfortunately, as awesome as radiology may be, you gotta get hazed before the ABR considers you worthy of the title 'radiologist'.
You are right... its way too early to worry about such things, and second so what? Short of giving up your first born or giving them a kidney, you are going to jump through what ever flaming hoops they tell you to if you want to be board certified. That means you will take the exam at their pleasure whether its your senior year or the year after.
Kinda like how I had to cough up 900 bucks for EACH step of the ABR, and book travel and lodging to take this friggin test in some random-arse hotel in BFE Kentucky!
Now, if you are still dying to know-- whatever the ABR says trumps any rumor that any current resident may have heard (besides none of the current residents will have to participate in the new format.)
If you really want to know, you can contact the ABR directly. Don't worry they won't bite... at least not the hand that feeds them checks for 1000 dollars for each step of the boards and the q10 year 2000 dollar check for the MOC.