Essentially, Yahoo! has published their browser matrix. In laymen's terms, if you're using Firefox 1.5 on Yahoo!, regardless of OS platform, you're getting what they're classifying as an A-Grade experience.
Since we're talking grades…K's nephew Gary, who we're putting through school, has also gotten straight A's at his school this last semester. We're very proud of him.
Back to Yahoo! though. In addition to releasing a browser matrix, they've also released a User Interface (UI) library and User Experience (UE) best practices. This is some good stuff, and about time. I know some of the folks who worked on this stuff at Netscape and this is some good advice.