This started out as a reply to Johan Larson's comment on this post, but it got out of hand, so I'm turning it into its own post. 

Actually, we've been doing originals for a number of years now -- the first all-new-material book was The Vampire Sextette edited by Marvin Kaye (back in 2000), but both Kaye and David Hartwell edited a number of anthologies for the SFBC starting in the '80s. In those older books, all of the stories were reprints, but the anthologies themselves were new, so they weren't quite as "original" as the recent batch.

The originals we've done since The Vampire Sextette are:

• The Dragon Quintet edited by Marvin Kaye (2003)
• Between Worlds edited by Robert Silverberg (2004)
• The Fair Folk edited by Kaye (2005)
• Down These Dark Spaceways edited by Mike Resnick (2005)
• One Million A.D. edited by Gardner Dozois (2006)
• Forbidden Planets edited by Kaye (2006)
• Escape From Earth: New Adventures in Space edited by Jack Dann and Gardner Dozois (2006)

And in the pipeline right now are two more: Alien Crimes edited by Resnick (a follow-up to Down These Dark Spaceways, with more of a "police procedural" slant) and Wizards edited by Kaye.

In recent years, I've also edited a couple of semi-originals -- Off the Main Sequence: The Other Science Fiction Stories of Robert E. Heinlein and Black Seas of Eternity: The Best of H.P. Lovecraft -- which were new collections of existing work.

And then there's Quantico by Greg Bear, which isn't a SFBC Original, but we were the first US edition, and we'll be the only US edition for a while yet.

So I guess the general answer to your question is: yes, we are doing a lot more originals lately. I think the members like them -- I know we like doing them -- but I'd love to hear people's opinions on the subject.