I can finally say something about this... I won! My entry was selected to represent the story "Midnight in the Heart of Midlothian" and will be included in an upcoming printing of the book. I can't wait to go to a bookstore and find one of my own illustrations in a book...
I have to admit that I had forgotten about this contest. I'd check the Halo Waypoint page once in a while to see what was up... It was a big surprise to receive the email. And an honor.
Here's the announcement: http://halo.xbox.com/en-us/transmissions/article/2010-08-16--Halo-Evolutions-Art-Contest-Winners