How Do You Handle Rejection?

So Shadow Mountain, the publisher I've been working closely with, provided me a glowing review of my middle grade manuscript, Lizzie Peterson and the Places of Naming, and said it's definitely a book they would consider publishing. Unfortunately, their slate for series is full through 2013. They will keep this book on their 'wish list' and stay in touch, but encouraged me to actively promote it to other publishers. Both exciting and a little disappointing. Gearing up for the next step. I'm going to target more national markets and research ePublishing.

So, what do you think? What should the next step be? How would you move forward?