Ari Balogh, CTO at Yahoo! just offered a preview at Web 2.0 Expo of a very new kind of Yahoo!. One that invites developers to take advantage of our huge scale to write applications that build on our existing properties (think Mail, Sports, Search, our front page, mobile, My Yahoo!, etc.), tap into millions of loyal users, and make Internet experience more relevant and useful.
Today we’re introducing the Yahoo! Open Strategy (or Y!OS for short), the details behind Yahoo!’s big bet to "deliver open, industry-leading platforms that attract the most publishers and developers."