YouTube's interface underwent some tweaks yesterday. Aimed mostly at improving community interaction with videos, ratings, comments, and search have been given more presence on the site.
The most dramatic of the changes is the commenting system, which now closely resembles Digg's with two buttons to recommend or bury a comment. Each comment gets its own ratings counter, and there's a master bar on the top of the page to sort comments within various rating thresholds. Once you've buried a comment it will disappear, and the system is set up by default to hide comments that are at -5 or below.
This is probably the most necessary addition I've seen to YouTube lately, as many videos, including unpopular ones, get a barrage of comment spam and off topic chatter. Already the new system appears to be getting a lot of use.
Ratings and search have been given minor tweaks as well. Users can now take a look at the recent rating history of a video, along with who were the last few to rate it. Likewise, each user profile now features a rundown of the last five ratings, similar to the "last watched" feature that YouTube launched earlier this year. As for search, channels have been given their own search module if there are more than 9 videos. Previously you'd have to sort through the channel's pages, or use a targeted site-wide search.