http://endurance-info.com/version2/a...nce-14297.html has some news about the 2013 LMP rules.
There are some minor changes in LMP2 regarding the cost cap and the displacement of diesel engines (i.e., Mazda) is limited to 2500 cc.
In LMP1 the hybrid capacity will stay at 500 kJ. So the increase to 1 MJ is not happening. Braking will be defined as 1G deceleration, whereas this year it was defined as 2G. Perhaps this means that there will be more hybrid activation zones on some tracks.