One of the feature that kinesis advertises for their Kinesis Advantage Pro Contoured Keyboard is:
Vertical key layout - keys are arranged in vertical columns to reflect natural motions of your fingers
Typematrix keyboard get advised with the sentence:
The Matrix Architecture (straight vertical key columns) increases typing accuracy and decreases wrist distortion.
Is there research that supports the notion that a vertical key layout is more ergonomic than the conventional key layout?