Wil Wheaton has a long rant blog post on the changes on YouTube we have already talked about here.
Google seems to be in the process of replacing the like/dislike button on YouTube videos with their Google +1 button.
This is not a widespread change yet as I cannot see this update on my own account. But a couple of users are reporting this and it might get implemented for all the YouTube account holders in the future.
Wheaton spoke about this change:
Where the thumbs up and thumbs down used to be, there is now a big G+ Like button. When you go anywhere near it, you get a little popup that tells you to “upgrade to Google plus” for some reason that I don’t remember, because the instant I saw it, I made a rageface.