"Newtype" is also a Japanese slang term for high-tech hipsters (circa 1974-5), stolen both from the Gundam shows and the magazine of the same name. Gundam created the term, the fans began applying the term to themselves (egotistical as they are), and the magazine was created soon after, catering mainly to those conceited otaku.
Publisher Kadokawa Shoten named it Newtype to market it as a hipper, younger "alternative" to the (supposedly) square (and at the time, the only) anime magazine Animage (sort of the IBM of anime mags - useful, but thought uncool because of it's age and size). The first issue of NT, of course, had a huge cover shot of a Gundam, and still covers the show(s) extensively.
The term "Newtype" is now used half-jokingly, in the same way a present-day American would use the words hipster or square. Referring to "high-tech" in the 70's compared to current technology, "Newtype" makes a good sarcastic name to call one who still has and relies on a Betamax or TRS-80.
There was also a fansub group called Newtype or NT-Anime, well-known for their near-flawless subtitling of all 96 episodes of Maison Ikkoku in the early 1990s, and are still widely respected in the fansub world for even attempting such a huge project.