Wikipedia Watchlist checks your watchlist and updates the badge on the browser action icon to reflect new changes. Clicking on the badge opens up a popup where you can highlight different changes to view both the edit summary and the time the change was made. Clicking the little 'd' will take you to the last difference for the page and clicking the page name will take you to the page itself.
What's new in version 188.8.131.52
ReleaseSeptember 10, 2010
Date AddedAugust 22, 2010
Operating SystemsWindows 2003, Windows 2000, Windows Vista, Windows, Windows 7, Windows XP