Cadsoft Eagle Version Control
Unfortunately there is not.

You could write a ULP script which creates a log of changes, but every change you make you would have to run the script manually. Essentially it would generate some form of list of parts, coordinates, values, etc. Then when you run the script it could compare the current values in the board with those in the log file and update them. Git could be used to version control the log file so you get a history of the changes.