Funny, I just started a somewhat similar github project covering ZeroMQ (in Ruby) over at:

http://github.com/andrewvc/learn-ruby-zeromq

If you're interested in highly concurrent network programming, ZeroMQ's pretty interesting stuff as well (it's not really a message queue, it's super-powerful socket).

It's only been up a few days, but given the dearth of ZeroMQ docs (especially executable ones in Ruby) some here might find it useful.

Direct link to the PDF so far: http://github.com/visionmedia/masteringnode/raw/master/book....

It seems a bit hard to follow, right from the outset. Maybe a dumbed down intro chapter or two is in order.

Looks promising. Be forewarned: this is a pre-alpha book -- not a lot there yet as far as I can tell.

Yeah it is very much a WIP, but it's a start. Currently includes roughly 4 complete-ish chapters, the build system etc, but I mean it is free so you cant really go wrong :)

Didn't mean to sound like I was being critical! I'm already a fan of this.

No worries :) just added epub / mobi :D