Interesting. I have been using a real scanner for years, and always knew that it was illegal in some states to use one in a moving vehicle. But like the article says, these apps arent technically using a scanner, they are just streaming audio. It will definitely be interesting to see how this plays out.
I for one use the Scanner Radio app all the time, as my scanner is an older one, and doesnt pick up the digital frequencies that my county/state now use. I frequently use the app to monitor traffic, emergency situations, and MOST importantly to monitor severe weather situations.