Sean Wallace has sold The Mammoth Book of Steampunk to Constable & Robinson (in the UK) and the Running Press (in the US) for a joint 2012 release.
He writes “I’m looking for both new and reprint stories, to fill out a 180,000 word volume, but for now until I get past the World Fantasy Convention, I’m just looking at reprints. If you have any reprints that you’d like to recommend, please feel free to help us out here.