I am using the updated wp 3.6.1 and latest Jetpack in win7 and updated Opera browser.
Very strange. I was working on my test install and found the footer was hugely long. I deactivated each of my plugins one at a time and found that if Jetpack was active that the footer would slowly grow taller and taller. I estimate it adds 20-40 pixels of height per second. I deactivate it and reload the page and it doesn’t happen.