Olney - 5:25 am on Nov 22, 2010 (gmt 0)
Looks like it's not occuring on all computers yet. My computer at home had the Google results, my computer at work has the old Yahoo results. My coworker who has the same IP & computer config as me has the Google results.
The number one easy difference between Yahoo results & Google is this:
Search for any keyword & attach the .com or .jp at the end. If the result comes up at any position other than #1 it's a Google result. If there is a page that resolves on Yahoo it is always #1 position.
I read that some expect Yahoo Japan is going to have "Powered by Google" on it. I might be wrong on this one but I doubt that is going to happen.