I thought it might be interesting to take a look at what I, as a Cybils Panelist, was offered this fall. 98 books were nominated in the middle grade science fiction and fantasy category of the Cybils Awards--all of these books were ones that somebody loved best. I read 96 of them.
Here are the kids of color I found, the ones who got enough page-time to be memorable. But please please keep in mind that I read them all in the past three months rather briskly, so my memories of them might be faulty and I am open to corrections!
Two of my comments have spoilers; I have indicated this by writing them under a SPOILERS warning.
First, a look at the covers. Yep, 8 out of 98 have kids of color on them. Two of these books (This Side of Magic, by Debbie Dadey and Marcia Thornton Jones, and The Taker and the Keeper, by Pat Perrin) never identify their characters in text as having any particular ethnicity, and I don't see why this can't happen more often.
Turning now to books where the text identifies kids of color as central characters:
One of the four kids who are the main characters in Century #1: Ring of Fire, Pierdomenico Baccalario, is from China.
The British boy who is one of two central characters in The Immortal Fire, by Anne Ursu, is black.
Night of the Living Lawn Ornaments, by Emily Ecton, has an African American boy as the number 2 main character.
The Prince of Fenway Park, by Julianna Baggott, has as its hero a mixed-race boy.
Quest for the Simurgh, by Marva Dasef, has a Middle Eastern cast of characters.
Where the Mountain Meets the Moon, by Grace Lin, is about a Chinese girl.
Kids of color as supporting characters:
In The Dragon's Pearl, a story of Marco Polo, by Devin Jordan, a supporting character turns out to be the daughter of the great Kahn.
In Hannah's Winter, by Kierin Meehan, all the supporting characters, dead and alive, are Japanese.
Jake Ransom and the Skull King's Shadow, by James Rollins, includes characters who are Mayan.
Roar, by Emma Clayton, includes supporting characters of various ethnicities.
In Stonewall Hinkleman and the Battle of Bull Run, by Sam Riddleburger, an enslaved boy is an important supporting character.
In Water, Water, Everywhere (Sluggers Vol. 4), by Loren Long and Phil Bildner, none of the kids are of color, but the African American character shown on the cover is central to the plot.
In When You Reach Me, by Rebecca Stead, one secondary character is black or mixed race (thanks Wendy!).
The Nine Pound Hammer has a very diverse set of kid-of-color supporting characters (the main character is a white boy), including the son of John Henry himself, who, unfortunately, dies saving the white kid.
The Last Olympian is memorable, POC-wise, in that the one black demi-god identified as such gets killed in the first chapter.
So. Only 18 out of 98 books (as far as I can remember) were at least a little non-white. I don't think this is because scores of middle grade fantasy and science-fiction books featuring kids of color weren't nominated--I can think of only one other from the relevant October 2008-2009 period (City of Fire, by Laurence Yep).
Our Cybils shortlist of seven books (which you can find here) fortuitously includes two books in which kids of color are the central characters--The Prince of Fenway Park and Where the Mountain Meets the Moon, both of which are great books. I dunno if the diversity they bring to our list added, in our unconscious minds, to their appeal. Whether it did or not, I'm glad they are there.