Finally I've had the time to dust the project off, upgrade some of the required libraries (node.js bumped from 0.4.2 to 0.8.11 in the meantime) and did some minor patching to get it done for some finishing touches and hopefully release somewhere this year.
We implemented the full real Tetris® (yeah, that means T-Spins and funky stuff Tetris addicts like) in MVC, with configurable renderers (canvas, ASCII, Divs), input methods (keyboard, swipe, touch), 2player split mode and offline singeplayer.
The multiplayer support is inspired by Tetrinet ( http://en.wikipedia.org/wiki/TetriNET ), powerups are all implemented but it's not yet possible to bomb one of your opponents.
I have no clue how the (self-hosted) hacked up node.js game server will perform , and there's no game rooms yet, but the basics work.
Please have a look, comments, suggestions and inspiration would be appreciated. How should we do the touch input for instance? I'd like it if I can be as good a Tetris player on my mobile as in the browser with the keyboard.