Here it is... Google again came with bang.
One of my client needed live Chat support on his web site. So I have tried lots of options including third party component, making my own chat system but than I came across the Google thing. Yes, you can add google talk chat support on your blog/Web site.
They call it Google Talk chatback badge.
If you want one for your own than go to http://www.google.com/talk/service/badge/New
They will ask you for login, after login you will be redirected to Create a Google Talk chatback badge Page.
Rest of the steps are very easy..
1. Select a title for your badge.
2. Write your nick name : ( Mahin )
3. Select Style depending on layout of your website or blog.
4. if you want to display your status message there then check the checkbox Show your status message.
5. Click update badge.
You will be given a script in below textbox, just copy and paste this script in your blog/Website.
How it works :
1. If your gTalk Status is Available ie. Your status icon is green ball 
then your nick name/Title will become hyperlink. ( If your status is busy then it will not be a hyperlink.)
2. When someone will click on that link
- he will get a popup chat window.
- You will get a chat from chatback.talk.google.com with one link. If you want to join this chat than click on that link.
- you will be redirected to your default browser to open a popup window. if you are not already logged in in to your gMail account than it will ask you to login.
- After login you will get Launch Chat button. Click on that and you will get a popup window, where you can chat with user.
Remarks :
1. Both party must have Flash 8 or higher plugin installed in their browsers.
2. System is quiet slow, so better you write warning about same in your blog/Website.
3. You should not put this type of things directly on your home page, because basically it is a cross domain request so it will affect the loading time of your home page. So better you put link for this on home page and open a pop up or new page for this.