New Yahoo! Interface

If you double click the message, it will be opened in new tab.

One more cool feature is, RSS Feeds are integrated into the mail itself. And if you subscribed to any in MyYahoo! All get imported automatically into the mail.

Drag and Drop messages to different folders.

New Hotmail Interface

If you double click the message it will get maximized.

You can even right click on the message

Drag and Drop Feature.

One of the feature i liked most while composing messages, the error checking is done similar to word.