Hello Albula et al,
Sorry to be late with this information, but I hope I have what you need.
Yes, the moped law passed and went into effect in July. I exchanged several emails with the Greensboro PD to see how they would interpret the law as it would apply to motorized bikes. So, the information I have is specific to GPD's interpretation, and may or may not be representative of how other departments may interpret the law.
In short, according to GPD, a motorized bike is a moped so long as it has two or three wheels, is under 50cc (the officer noted the lag between the legislation and the state of alternatives to ICE technology), and has a top speed of 30 MPH or less.
To legally ride a motorized bike (moped) in NC, it needs to be registered and tagged. NC tag offices can register a resident's homebuilt vehicle (although lights, etc will likely need to meet DOT standards). Also, while operating, a DOT approved helmet must be worn. Insurance and driver license are not required.
Prolly not the answer hoped for, but I hope this helps