Well this is interesting! LiveJournal now has a feature called "LJ-Like", which adds "Like" buttons at the bottom of your post. You put a <lj-like> tag into your post, and boomf, there they are. There's also <repost button="repost">, which will add a "repost" button at the end.
I'm not sure why it needs to be explicitly put in, instead of being the default setting, but still, it's nice to see LJ trying to get more social. The quick-and-easy-sharing ability of other sites is one area where LJ could use a little modernizing.