Apparently they're going to be open to submissions from all comers in September:-
'Write with wild Abaddon!
Shared-world imprint celebrates sixth birthday with open call for e-novella submissions
For the past six years, Abaddon Books has been publishing genre-busting novels from break-out authors and in brand new formats.
So to celebrate its birthday this summer, we are is calling for open submissions for our new e-novella series.
Starting later this year, Abaddon will publish a series of brand new e-novellas – and authors can either play in one of our ten shared worlds or create their own!
Whether you’ve an agent or are going solo, whether you’re an established writer or trying to get your first project, we’re interested. Our books are pacy and action-filled, but smart and sharp, with characters that pull you in and challenge you. And our stories are dark, whatever the genre.
Since 2006, we have published almost eighty original novels in ten shared-world series, and have given the world the talented and irascible Chuck Wendig his fiction debut, not to mention the wildly imaginative Al Ewing. It has uncovered Kitschie-nominee Scott K. Andrews, and gave the brilliant Gary McMahon, Pat Kelleher and Toby Venables their mainstream fiction debuts.
If you know Abaddon’s work, you’ll also know what we like. Choose a genre, make it fast, make it tense, make it dark. And make us care about your characters. Make it original! Make us want to come back and see what happens next.
Submissions will be open for the month of September 2012, from midnight BST on 31st August to midnight on 30th September.
For full details on the submissions process, go to http://www.abaddonbooks.com
Happy birthday, Abaddon Books - let's make it one to remember!'