When existing mod is updated, no message about this appears on the “Activity” page or in the release topic. Usually the mod’s author has to write in Status Updates or manually create the post in the mod release topic to let people know about the fact.
Currently, to view recently updated files, user has to open Downloads page, select the game and one of the subcategories, then open “sort by” menu and choose “Recently Updated” menu item.
There is a “Follow” button on the mod page, but it’s not the same: if you “follow” the mod, then you will receive notifications about not only updates, but also about every new comment (<- I'm not sure that I remember correctly this one); also sometimes you may become interested in mod after update and sometimes you just want to quickly see which mods were updated recently.
I have 2 suggestions about updated mods:
It would be very useful if “Recently Updated” tab was added to the “File” section on the site’s main page (in the right part of the page). This way people will be able to switch between them with one click (like “First post/Latest post” in the preview window of topics).
Make it so that the message appears on the page "Activity" when the mod is updated.