There's no end to stories about how Google either does or is suspected to filter its results for China (with news, it does; with web search, China itself does). Nice to see it getting a break and Yahoo instead taking a slam for doing search filtering. That's covered at the end of this News.com article, When blogging can get you locked up, spotted via Dave Winer.
It's not a new discovery -- just one that generally is overlooked due to the usual "It's an all-Google-world obsession."
Neither search engine makes disclosure of filtering, when it happens. They ought to. Got To Censor Search Listings? Why Not Disclose?, China Blocks Google News -- So Bring On The Disclosure and Revisiting Google Censorship In Germany & France explain more about how and why they should do so.