There are no significant changes that I've heard about.
As I understand it:
The rule on hunter bbl length has been clarified -- 26" is the OVERALL length, including any tuners. (The original wording left some wiggle room about where the measurement should end.)
And the rule on defective cartridges has been redefined. From now on, only cartridges that are clearly struck by the firing pin and fail to fire will qualify. Screw-ups by handloaders are no longer acceptable alibis. (There have been some really poor/sloppy/potentially unsafe handloading procedures in evidence at matches -- uncharged rounds, undercharged rounds, reversed primers, improperly sized cases, etc. -- and sloppy loading will no longer be justification for alibi shots.)