One of the best Morrowind mods, Morrowind Advanced, was created by a Bethesda developer, Worm God. There is a Skyrim mod on Steam Workshop right now that adds real-time carriage travel, made by a Skyrim dev. Off the top of my head, that's all I can think of.
Just tested it, on a trip from Riften to Windhelm. Awesome concept and it could really add to the immersion, but it needs more polish. Cart-riding down hill sides is good fun though. Haha.
Besides, the roads are really too small...