Yes, long awaited feature of saving history at servers has been provided by Yahoo Messenger. So, now, whatever chat you do online will be stored and indexed by Yahoo Servers so that you can search the history anytime no matter where you are! But, I have got First experience as BAD experience. This is what I am getting..
Though, I am not sure if they also saves the history for chat that we do with normal desktop installed Yahoo client! If its also there, it would be cool, isn't it?