On every thread or post, if you click on more and activity, you'll get the info.

I personally find this to be a good things, I've seen people using downvote way too easily. I like the idea that we need to be somehow accountable for those mechanism.

edit: It could be somehow improved to have an option to let this info only available between concerned users.

edit edit: I think that up/downvote info shouldn't be public, but kept private between the users involved. we need to address this privacy issue.