Thanks much for all the kind words everyone! I'm glad to see that people are able to get some use out of the book.
In retrospect I think devoting so much of the book to the organizations just in New York detracted from more general utility, but I had these ideas for influence I wanted to get out there. Even those I now think could use a fair bit of simplifying.
One issue I had when designing the book and choosing what to include, is that I suspected a fair number of people would get more use out of a toolkit than a setting, since they might use their own world or a previously published world, as their version of the Second World. That idea seems cool to me too -- I've contemplated running a Second World-Eberron game.
I would like to release minor updates and modifications every so often to the core book as I figure out what rules could use changing or based on suggestions. I'll do this simply as updates to the files here at ENWorld and RPGNow -- but not too often since, as a customer, I know that too frequent updates sort of get lost in the shuffle.
Derek asked if I'd be releasing any new material for the Second World. I'd still like to do the Tone Warden and Pattern Warden, but there's so much nice and innovative new magic material available from various places that I think there's not a lot I could add.
I'm also afraid I have a bit of ADD in this regard -- right now what I'm planning to do is put together a d20 modern campaign length adventure based around a new Scanners-esque psionics system. I figured we don't actually have one of those, and it'd be particularly interesting if players could be introduced to new powers during the course of the game as opposed to knowing it all from the very start. This way, learning about their secret capabilities becomes part of the exploration of the game world.
Also, I think d20 Modern offers a unique chance to set players in a world they're familiar with, yet one that can include surprising revelations as the characters discover hidden places or secret organizations.
Needless to say, that's a bit ambitious and I'm also busy doing other writing -- but hopefully it won't take too long.