The photo in the following link was taken in South Luangwa NP in Oct. I did not see the color in the wing as it apparently flicked its wing just as I took the photo. None of the birding experts could identify it, until I sent it to "BirdingWith Bob", he has a web site with that name, and lives in Livingstone in Zambia. He is a consultant ornithologist and I was fortunate to be able to bird with him for 3 hours one morning. He suggested that the blue was really white and the light reflection was just right to make it look blue. The bird is really a White-browed Scrub-Robin.

http://s174.photobucket.com/albums/w86/hughbirder/Zambia%20Birds/?action=view&current=White-browedScrub-Robin.jpg

Hugh Jennings
hughbirder at earthlink dot net
Bellevue, WA