The "Mexico City Policy" was instituted by Reagan, reversed under Clinton, and re-instated by George W. Hopefully Obama's decision won't be just another flip of the coin, especially since this policy has sweeping consequences for health care around the world.
While it's easy to see it as a pro-life/pro-choice debate, the policy itself has larger effects, as organizations that may not offer abortions, but provide abortion counseling, would not be eligible for any funds, despite offering other services such as AIDS care or other forms of birth control. Oh yeah...and it imposed the personal beliefs of one sector of the United States onto the lives of citizens of other countries! (That's a lot of modifiers! But you get my point.)
Obama: the provisions of the policy "are unnecessarily broad and unwarranted under current law, and for the past eight years, they have undermined efforts to promote safe and effective voluntary family planning in developing countries." International family planning "has been used as a political wedge issue...my Administration will initiate a fresh conversation on family planning, working to find areas of common ground to best meet the needs of women and families at home and around the world."