Yahoo is testing out its latest front page interface that will allow applications to run separately, accelerate performance and allow code to be portable.
The effort built on the Yahoo User Interface 3.0 (YUI 3.0) is interesting. The front page is built to be open to developers and users for tweaking.
Yahoo's Nicholas C. Zakas has more detail. The Yahoo front door is being bucket tested, which means you may randomly stumble across it.