The Original Series: The Continuing Missions, Volume I
Contains The Rings of Time, by Greg Cox, That Which Divides, by Dayton Ward, and Forgotten History, by Christopher L Bennett's. Reusing the latter book's cover:
Typhon Pact: The Khitomer Accords Saga
The three most recent Typhon Pact branded books: David R George III's Plagues of Night and Raise the Dawn, and Una McCormack's Brinkmanship. This time the first book in the collection contributes the cover art:
Destiny: The Complete Saga
All three books of David Mack's Destiny trilogy, which like the recent trade paperback omnibus of the trilogy uses the Mere Mortals cover art.
UPDATE: David Mack has been able to confirm this ebook omnibus will include the slightly revised version of his trilogy from the trade paperback omnibus (rather than the untweaked original versions)
All three will be available to download onto your ebook reader of choice in Janaury.