gmail now can reply in a chat-window, when the contact is online. The Chat-History then is saved in the email-conversation.

http://mail.google.com/support/bin/answer.py?answer=34539&hl=en
http://www.jmboard.com/gw/2006/06/01/gmail-verschmilzt-emails-und-chat-noch-weiter/

wow..
cool

thanks for the info!

more..
here:
https://mail.google.com/mail/help/about_whatsnew.html

It is a nice feature. Works well.

http://googleblog.blogspot.com/2006/06/reply-by-chat.html

That's a slick little feature. I can think of occasions where I wanted something like this. Sometimes replying to an e-mail just isn't fast enough (!) -it's also good for those 1-word replies.