UberX cars still have towncar licenses though, judging by the TCP stickers on their bumpers.

In Chicago I've seen taxi drivers using Uber X, but that may be a city-specific pilot. This TC interview with Uber indicates that Uber X drivers have TCP licenses, but may not necessarily drive limos or town cars:

http://techcrunch.com/2012/07/01/uber-opens-up-platform-to-n...

Uber also has extended their service to include some real taxi drivers in San Francisco (which would have a normal taxi license)