Never, to judge from the introductory copy on the TextMate web site. Which I think is a pity, since the editor has some real strengths (although nothing that isn't more or less already available in Vim or Emacs, near as I can tell, if slightly less flashy).

I've played with TextMate a bit, but simply can't commit to learning an editor confined to a single operating system. That way lies Madness, or slower editing everywhere at the very least ;-)