Many of us have enjoyed Star Trek Vanguard:Harbinger, the first in the series by David Mack, and wondered why they would include that as a sample text with the reader if they weren't going to sell the next book in the series.
Well, they have it at Connect now. (Maybe they also had it before and we just missed it?) Here's some info on the series...
http://memory-alpha.org/en/wiki/Star_Trek:_Vanguard
If you search for "Summon the Thunder" at connect, you'll find it!
The next book is Reap the Whirlwind, which is due (in paper, anyway) on May 22, 2007.