The new update allows the scale to Tweet your weight and other info. The scale is capable of measuring your weight, BMI, lean and fat mass and tracks your goals. I am not sure that most people who are using the scale in an effort to lose weight will want everyone on Twitter knowing how much they weigh.
Withings points out that the Twitter feature will not be enabled by default. The setting will have to be enabled specifically by the user. The Tweet will post the users weight and how many popups they need to gain or lose to reach their goal.