There is a great discussion over on Slate about how the FBI sees it's ability to listen in via tapping phones as "going dark". Why use a landline or a cell phone when you can use your webcam to orchestrate your criminal enterprises?
The blog suggests that the FBI is interested in extending CALEA, the Communications Assistance for Law Enforcement Act, to cover Gmail, Google Voice, and other cloud services. This isn't a new thing exactly. Law enforcement has been working for some time now to figure out how to apply CALEA to VoIP, for example. It was only a matter of time before Instant Messaging fell under that same category.
Kids today prefer texting to talking anyway.