What is a new collar worker?

Do you mean "Blue Collar Worker"? If so, that is a menial laborer. Someone who wears a uniform. As opposed to a white collar worker - someone who wears a suit and tie.

The new collar worker is someone who is professional but whose dress is casual. You can see new collar workers in Silicon Valley. All of these workers make a substantial amount of money, but go into work with a laid back presentation.

Looking up your phrase I found the traditional white collar class and the blue collar class of worker. It seems that a subset of blue collar has evolved and it is called "gold collar".
White collars are the doctors, lawyers, bankers and managers.
Blue collars are the (typically skilled) manual labor portion of the work force. These include mechanics, truck drivers, machine/equipment operators and other craftsman types.
The "new" class of worker is "gold collar".
http://en.wikipedia.org/wiki/Gold-collar...
Despite the description, these are not high-end workers, choosing instead of investing or saving money, to indulge in material goods. Rather than having "sensible" possessions, these folks will look like a million bucks but be in debt for two million.