Our friends at the Guttmacher Institute took a look at the study and noted something significant (pdf):
An abstinence-only intervention aimed at young, urban African-American adolescents successfully delayed sexual initiation among participants in the program, according to a well-designed new study, "Efficacy of a Theory-Based Abstinence-Only Intervention Over 24 Months," by John B. Jemmott and colleagues. While the evaluated program is the first abstinence-only intervention to demonstrate this positive impact in a randomized control trial, it was not a rigid "abstinence-only-until-marriage" program of the type that, until this year, received significant federal funding. The evaluation, therefore, adds important new information to the question of "what works" in sex education, but it essentially leaves intact the significant body of evidence (pdf) showing that abstinence-only-until-marriage programming that met previous federal guidelines is ineffective.This is an important distinction, and it will be useful information to have at one's fingertips when the Jemmott study is used by abstinence-only until marriage advocates to argue that abstinence-only sex ed is effective.
This study isn't a game-changer. Reproductive rights advocates who have long championed comprehensive sex education have always been in favor of including information on abstinence. (That's what makes it comprehensive.) The difference is that feminists endorse making abstinence merely one part of a broader sex ed curriculum, and don't endorse linking abstinence to marriage.
So basically this study, if anything, reinforces the existing position of comprehensive sex ed advocates. It doesn't lend credibility to the resoundingly-debunked position of abstinence-only until marriage brigade.
If we had responsible media, that might have been clear.