We cover many Google algorithm updates here but not all the international ones. A big one hit Google Japan this morning, specifically aimed at targeting low quality web sites and lowering their rankings in the Google Japanese search results.
The translated version said:
As a part of this, we made improvements to the quality evaluation method of the website this week. This update will lower the ranking of lower quality sites that focus on having your page displayed above the search results rather than providing useful and reliable information to users. As a result, high-quality sites with original and useful content will be displayed higher.
I do not know if this was a Google Panda tweak for the Japanese language or something completely different.
Kazushi Nagayama from the Google team involved in this release did say on Twitter that this release ONLY impacts the Google Japanese results, not anything else.
So for all you folks in Japan who read here, hope you did well with this update.
Forum discussion at Twitter.