I have always thought that the logical direction for chat and email was the same. At some point in the future the only difference between them will be if you are there to answer the chat. Looks like Google gets this as well.
Email, chat, etc… is just communications. So how do you break down those communications. There is a sender and a reciever and a payload. The sender can set an importance and a responsiveness factor to the payload. Then the reciever can also set an importance and a responsiveness factor based on either the sender or the contents of the payload. In the end, the whole converstaion be it email, chat, voice communications, static web content, etc… should be saved in one space. It's good to see Google start to get this.
And why stop at email and chat? I can see all communications which need human points of contact using a universal interface.
Here is the story: Reply by chat