According to MLB Rule 6.08:
The batter becomes a runner and is entitled to first base without liability to be put out (provided he advances to and touches first base) when—
b) He is touched by a pitched ball which he is not attempting to hit unless (1) The ball is in the strike zone when it touches the batter, or (2) The batter makes no attempt to avoid being touched by the ball;
If the ball is in the strike zone when it touches the batter, it shall be called a strike, whether or not the batter tries to avoid the ball. If the ball is outside the strike zone when it touches the batter, it shall be called a ball if he makes no attempt to avoid being touched.
This rule came up a few times this year as players were not awarded first base when they were hit by pitch. There was a crack down in high school this year because managers were instructing high school players to allow themselves to be hit more often.
In talking with the umpires, I am hoping a less stringent interpretation of "makes no attempt to avoid being touched by the ball" is enforced down the stretch. At a minimum however, players should at least turn away from the ball and not simply watch the ball hit them. It is understandable that as a player steps and loads he might not be able to make much of an attempt to get out of the way, but something exceeding holding still when it is recognized the ball is coming inside should occur. Sticking out an elbow or thigh to be hit will certainly not result in a base being awarded.