Hi. I love These Broken Stars and I was just wondering if the second book has come out?
Sorry this answer is so belated--I don't come often to Goodreads (that way lies madness) and it doesn't email me when I get a question. Sorry!
To answer: no, the second book, This Shattered World, isn't out yet. It comes out on Dec. 23rd in the US, and you can find out more here: http://www.thisshatteredworld.com
There is a free digital short story out right now (thesebrokenstars.com/eshort) which adds a bit to TBS and explains a few things that were only hinted at in the book itself. It's not strictly necessary to read the e-short before reading TSW, but if you're looking for something to tide you over, there's at least that! (And it has the first three chapters of TSW in it.)