im seeing it in the UK now.
they may as well go the whole hog and just show the full size image when you hover over the first time, because the website owner gets next-to-no benefit when they click through anyway.
you can hardly see the web page beneath the image, and you cant even scroll it down until they click and close the image.
if a user wants to visit your site from google images, they have to 1) hover over the image, 2) click on the image, or the URL (because they both lead to exactly the same place anyway), and 3) click to close the image.
that is three separate moves before they can view your page.
one other subtle change that ive noticed is this:
they no longer offer the page's URL to click on. they offer the image's URL instead. so whether the user clicks on the image or the URL, they still cant jump straight to the page without seeing google's new overlay first. sneaky.