I remember seeing that on the net a few years back. I even practiced it (and it's not difficult to master), BUT though it looks perfect from the front, I recall some issues with it -- I don't think it is as stable as the "standard" way to fold a t-shirt -- that is, if you are dealing with lots of shirts, putting them in a stack, moving the stack to a drawer, removing a shirt later from the stack (not necessarily the top one) .. the stack does not stay as neat as with the standard fold.
Still .. it's a pretty cool thing to show someone .. "... and this is how to fold a shirt." (OK, I admit it HARDLY ever comes up in real conversation.)