The new browser is named Axis and it became available today.
Direct to Yahoo Axis Web Site, Download Info
Axis is available for all three screens: PC (as a browser plug-in), the iPad and the iPhone (as apps). Android is coming.
Axis is a fully functional browser that syncs content across all screens if users are signed in. Like other browsers Axis features tabs and book marks and can render any web page.
On the PC it functions more as a “companion” search bar at the bottom of the page on each of the major browsers: IE, Chrome and Firefox.
2. Official News Release: “Navigating a New Course In Search — Introducing Yahoo! Axis”