The minds of Silicon Valley have yet to find the cure for tardiness, but they have figured out a way to make being late less rude.

A new app call Twist notifies friends and colleagues when you’re running late, calculating the estimated time of arrival to your destination on-the-fly and zipping off text messages to the people waiting for you.

The free app, available on Wednesday for iOS devices, can be used for trips by car, bike, foot and public transportation in most major U.S. cities. In development for the past year, the app’s algorithms crunch through various data streams, such as the average speed you travel and real-time traffic patterns, to calculate ETAs that co-founder Mike Belshe says are 98 percent accurate.

Belshe, a former Google employee who was a founding member of the Chrome group, teamed-up to create Twist with Bill Lee, a serial entrepreneur and angel investor who has backed Tesla and Posterous.

“A lot of guys are just focused on ‘where,’” said Lee, referring to the spate of location apps that have flooded the App Store in recent years. “We’re the first to focus on ‘when.’”