If you've been out and about lately you may have noticed the not so new trend of e-cigarettes.
You'll see people with hand held vaporizers, some with blue tip, some look like futuristic pipes, and some look just like cigarettes, but instead of smoke they emit an almost odorless vapor.
It's a fast growing industry worth more than $1.5 billion, and as of right now it's largely unregulated. But that might change soon. For more on that, we're joined by Megan McArdle who wrote about this for Bloomberg Businessweek.