So I have finished a short story, titled Two in Hand, which is a little bit of a follow-on to Twice as High. It is two years after the events of TaH and follows Maddy, Kyle, and Julian on a little adventure. The adventure gives you a little more of a glimpse into the Tlin and what they're up to and introduces you more fully to the characters in the next Tlin novel--Tracker and Casey.
The short story will be part of a HUGE charity anthology coming out in August featuring a bazillion (okay, really more like 40) different authors and chock-full of awesome. I'll keep you posted on that.
In the meantime, as I said, the next Tlin novel is Casey and Tracker, and it's coming along nicely. I have another one 2/3 done, but that's going to be the 3rd or maybe even 4th one. We'll have to see where those events line up.