You can read more about Jennifer's project at http://www.cmu.edu/homepage/innovation/2008/winter/one-cold-... or watch a presentation about this project at http://www.allartburns.org/dorkbot/dorkbot-200801-jenn.m4v (244 Mb M4V)
To me, a mitten is a type of glove. But I'd be willing to believe that where the author lives the semantic relationship is commonly understood to be the other way around.
It's 2013, you don't have to wonder. Look it up!
It does absolutely nothing to address the entirety of my question - an answer to that would require some comparative scholarship on actual usage in various regions.
A mitten is defined as a "half glove" http://www.etymonline.com/index.php?search=mitten
So all mittens are also gloves.
"a covering for the hand made with a separate sheath for each finger and for the thumb." http://dictionary.reference.com/browse/glove
"a hand covering enclosing the four fingers together and the thumb separately." http://dictionary.reference.com/browse/mitten
But these common online dictionaries disagree with you. These are the two that I usually use and they both agree so I did not go looking further. I'm sure there are other dictionaries that might not define them this way.