The LJ "like" notifications are about the most useless thing ever. For me, such a feature is in the "meh, I wouldn't probably use it and don't really care, though I can see why some people might want it and on the other hand 'oh no not more Facebook'" category. But that said, the notification is just a link to the liked post, with no other information, particularly not WHO THE USER WAS. I'm not even certain how people are managing to like any of my posts, since I have a legacy theme on my journal that doesn't include those kind of elements (although for that matter I don't even see it on, say, news - maybe it's only viewable if you're in the "feed" mode of reading a friends page? their supposed screenshot on http://news.livejournal.com/151114.
html doesn't at all look like what I see). Even more confusing is when I get random "like" notifications for ancient posts (well, 2011) in random communities like rifftrax. It's like someone is sending bots around liking posts, or something... but if so, why?