The next book (Number four!) in the Gentleman Bastard sequence is The Thorn of Emberlain, and I'm already hard at work on it. I've also got a pair of novellas, The Mad Baron's Mechanical Attic and The Choir of Knives, that will bridge the time between The Republic of Thieves and Thorn. Those will be available from Subterranean Press. I've also got several short stories slated for publication or in the works; one for the Clockwork Universe: Steampunk vs. Aliens anthology, and one already written for the big Gardner Dozois/George R.R. Martin theme anthology Rogues, available some time in 2014.
Full interviewhere.