Since there's NO block that outputs a redstone signal (and by that, I mean a block. Not a redstone torch, not a NOT gate, something that you can place on a wire, pipe, or cable), I've had to use batboxes to output redstone signals when they're empty (and never fill them) or, in tight situations, fill them with energy and just have them not output it and output a redstone signal instead. The redstone blocks are going to be an incredibly cheap and awesome alternative.
I feel kinda bad that Eloraam just put in redstone blocks, to have them be replaced by something vanilla.
Also, keep in mind, for people who play vanilla (Etho, doc, sethbling, etc.) this is a HUGE update. Too bad we can just look down upon them and beat them with our railcraft priming tracks.
The cube chunk thing sounds interesting, I drop to 4 FPS while looking downwards and go up to 146 while looking upwards. That'll really help.