Here (computerandvideogames.com) and here (pcgameworld.com) are interviews with the lead designer for the game. He talks about some of the new content (which will eventually be available for download via X-Box live, so fret not, X-boxers) and other aspects of the game.
Also, here (pc.ign.com) and here (gamespot.com) are some hands-on previews. They don't say much more than that the game will ship something this November. (I *know* I saw it say somewhere that the date was 11/18, but I can't find that now for the life of me...)
...and I feel very, very old. I don't know when I first got into Tetris - I know it was in an arcade in Kelowna, sometime around 1988 - so I missed some of the first few years, but it still wins my vote for best game ever.