It's a really weaksauce version. 10 days after you first launch a game/app, you can see how long you have used it... in 5 hour increments.
So if you played 32 hours of Zelda, it'll say "Over 30 hours played" when you hit 35 hours it'll say "Over 35 hours played" etc. Laaaaaaaaaaaaaaaaaame.
Better than nothing, I guess *lol*. I need to check again, I have two games now that should be beyond 5 hours.
Activity logs are something I like about Nintendo consoles, ever since they introduced it with the Wii. I actually prefer that to trophies or achievements, which only tell you the date you did clear some part of a game.