One Good Knight (A Tale of the Five Hundred Kingdoms) by Mercedes Lackey.
This book is a sequel, of sorts, to The Fairy Godmother. I enjoyed it; it's a nice light read. The main character is a princess and a dragon comes to ravage the kingdom. Luckily, George is on hand to save the day. Of course, things aren't what they seem. I saw a lot of the plot twists coming in advance, but they were still fun.
The characters from the previous books show up, but it's mainly told from the point of view of the princess. The next book in the series (Fortune's Fool) comes out in two weeks.