I recently took these two picture from the window of a Dash-10 Turboprop. Camera: HTC Desire HD. I can assure that the blades looked normal to the naked eye. Any explanation on the observed warping of the propeller blades in the pictures?
Oscar Gemperle sent me the solution as explained in another blog:
http://blog.alexbeutel.com/135/image-aliasing-of-plane-propellers-in-photos-and-video/
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HellmuthBroda.com (Pondering Technology) 
Oscar Gemperle sent me the solution as explained in another blog:
http://blog.alexbeutel.com/135/image-aliasing-of-plane-propellers-in-photos-and-video/