Facebook "Like It". Google "+1". Assuming Google A/B tests just about everything, I'm surprised "+1" seemed like the winning choice. I don't hate it, I'm just surprised...
The problem with 'liking' something, which would be especially acute on Google, is that it just sounds downright wrong for some things. Perhaps you're looking for news on the Japanese Tsunami. No, I don't 'like' it. Yes, it's relevant to what I'm looking for.
Facebook's Like button can be either "Like" or "Recommend", and publishes the selected verb into news feed. Many news sites use recommend for this exact reason (NYT, for example).
Still valid argument on the meaning of the like or recommend verbs in certain contexts. Eg someone may write something I disagree with and I don't want to like or recommend it but I may +1 for being articulate or a point well made. Geek in me and maybe too many q&a sites but I think +1 works