It has to do with Medicare Part D. It’s a hole in prescription drug coverage that meant many seniors had no way to pay for expensive medications they needed.
In 2010, people crossing into doughnut hole territory will receive $250.00 to help. In 2011, a 50% discount on brand name drugs will go into effect, further assisting seniors. In 2013, the government will begin subsidizing certain drugs.
In all, by 2020, the doughnut hole will be reduced by 75%.
LA Times has a piece on the changes that does a good job of spelling it out.