In addition to what you say, it's also a matter of community. If the article is on some stranger's blog, I'm more likely to post here. If the article is on a

In addition to what you say, it's also a matter of community. If the article is on some stranger's blog, I'm more likely to post here. If the article is on a site where I feel like I'm already part of the community (say, Metafilter, or JOS (in the past)), I'm more inclined to post there.