The new technique is a modification of a familiar concept of "buffer zones" that determine where other cars are going and how likely the driverless vehicle is to avoid a collision. Earlier systems calculated those zones in advance to save time, but MIT uses a "mathematically efficient" approach that creates new zones on the spot if performance falls well below that of a human driver. The process is skewed by speed and can even be customized based on the level of aggression, although there's always a "safety guarantee" that should spare you from having to swerve.
This is just an algorithm and may not reach the road for a long while. Toyota is backing the project alongside the Office of Naval Research, though, suggesting that it's just a matter of time before this enters real-world service. And it might be more important than it seems at first. If self-driving cars are going to coexist with humans, they'll need to blend in with human traffic patterns -- and that means changing lanes more often, even if it's just to get around slow drivers.