I'm so sorry, I read your post too quickly. :)
It looks like the Posts I Like widget is working but there's a delay in updating posts, much like there's a delay in updating stats. You should see posts you've liked show up the following day.
Since I can't view a list of posts that you've liked to test this, could you keep an eye on it for me and let me know if it's regularly not working? If you're still having trouble, it would help to know more specifics: which of your blogs you're having issues with; the post links (like you shared); when you liked the posts; if none of your recent likes are showing up, or just certain ones.