Update: Since this item ran, there's been a lot of discussion about the wisdom of withdrawal – and how effective this method really is. I think I was a bit too flippant about the issues involved so I though I'd take another look.
For one thing, the comparison data is based on the fact that many people don't use condoms correctly, lowering their effectiveness. Given that reality, withdrawal may work as as well. But since it does nothing for preventing STDs, isn't it better to get the condoms right?
From Caroline Hotaling, an analogous situation:
All of the drinking water guidelines that existed (at one point anyway) for uranium in drinking water were based on its toxicity, not on the fact that it's RADIOACTIVE. Why? Because no amount of uranium in drinking water is safe if measured by its radioactivity. Who the hell cares whether pulling out is as effective in preventing pregnancy? It's frickin 2009, people. Use condoms.
Yes people. Use condoms.
Vindicating every boy who ever promised to pull out and actually did, here's a fascinating study from the Guttmacher Institute:
A new commentary, “Better Than Nothing or Savvy Risk-Reduction Practice? The Importance of Withdrawal,” by Rachel K. Jones et al., published in the June 2009 issue of Contraception, highlights that withdrawal is only slightly less effective than the male condom at preventing pregnancy....
The best available estimates indicate that with “perfect use,” 4% of couples relying on withdrawal will become pregnant within a year, compared with 2% of couples relying on the male condom.
More realistic estimates suggest that with “typical use,” 18% of couples relying on withdrawal will become pregnant within a year, compared with 17% of those using the male condom. In other words, with either method, more than eight in 10 avoid pregnancy.
This method is of course all about contraception, since you won't have any barrier to STDs without a condom.