A nation faced with an ever-worsening space crunch, Japan is presently hot for N scale model railroading; much more is available there in 1:160 than most Americans realize. They are also now beginning to get serious about Z scale, too (surprising that they didn't invent Z).
In a bid for the world's smallest commercial model trains, Eishindo of Japan launched a new scale: T, which stands for three, the distance between the rails in millimeters. It represents a significant leap in size reduction; whereas Z scale is only 25% smaller than N (1:220 vs. 1:160), at 1:450 T is over 50% smaller than Z.*
A few things about T are clear from this modeler's view. First, it will almost certainly remain a novelty, never to be accepted into the ranks of serious model railroading scales (as it is, Z just barely made it in the door). A good part of this of course has to do with the fact that the size imposes serious limitations on what sorts of rolling stock can be manufactured; it would appear the scale is based on the smallest possible model that will fit on a mechanism powered by a pager motor.
Then there's the practical aspect of handling the models: many people will have enough difficulty just placing the cars on the track, let alone working with 1:450 people, who stand a mere 3/16-inch tall. The likelihood of seeing functional turnouts is pretty slim, and any form of operation would probably be out of the question. Plus, with a market size smaller than the scale itself, prices will be comparatively astronomical.
T Gauge might be regarded by some Z scalers as a means to model narrow gauge. However, T measures out to just a shade under 30 inches—an odd size at best. And modelers will be faced with many issues, not the least of which will be the need to scratch-build just about everything except the track, at which point one may then question the underlying value of the idea in the first place.
I happen to think that it might be fun working at 1:450 (if nothing else, there would only be a handful of us worldwide). I'd like to see if an E or F diesel could be fashioned around the mechanism, and maybe start with a classic passenger train. Building any kind of rolling stock will be quite a challenge, though. Modelers seriously interested in pursuing T should probably be prepared to learn the art of metal etching. And obtaining parts such as wheelsets will probably be futile, so someone would need to start turning their own.
Perhaps the existing Japanese cars are close enough to some North American commuter trains that a little paint and detailing would do the trick; then I might be tempted to model something along the lines of, say, a New York mass-transit railroad. I think it would be fun to create a dense urban landscape: at 1:450, several city blocks would fit on a bookshelf, and skyscrapers could be rendered accurately without being imposing.
Why am I even interested in T? Two reasons. One, I have a Japanese-like space crunch issue of my own at the moment. And two, I have a tremendous fascination with very small model trains. I might try my hand at building a shoe-box railroad. Or I may wind up simply placing the loop of track on the corner of my computer desk for amusement. One way or another, though, I will have some T.
*I am deliberately ignoring the previously-introduced ZZ Scale, 1:300, which is a battery-powered toy with plastic track, as opposed to T Gauge, which is powered through the rails with a throttle. The quality of T looks impressive, and when it does hit the shelves, the product line will include structures, vehicles, trees, people and many other items—enough for a complete layout, which is presently not an option in ZZ.