Version control systems typically call this feature “blaming someone”. For each line, it shows you who modified it and when.
Update: I’m looking for a solution for articles with thousands of edits as well (i.e. navigating the version history and checking each one is not practical).
If you click the
View History link for an article you can see the list of changes made to the article, on what date, and by whom. A short summary of the change description is also displayed. You can then click the
Compare selected version button to compare text.
Unfortunately, I’m not aware of a Blame feature that lets you directly see who made the changes to a particular line or sentence or paragraph.
EDIT: You may want to check out Greg Hewill’s site, he (apparently) is working on just such a blame feature.