My good friend and critique partner Marie Tuhart sent me the news that Silhouette is opening up for pitches on Nocturne submissions.
Although the "Call" includes a link to the writing guidelines for the shorter-length Nocturne e-books (called "Bites"), the comment thread clarifies that this call is for full-length novels. The moderator of the site does indicate that she will check to see if they are open to Bites submissions as well.
If you're not familiar with Silhouette, it's a division of Harlequin. The Nocturne site is here. Their writers' guidelines are here.
And go here to read the call for submissions.