how can i create gtalk bots. I have seen tutorials for making AIM bot here.http://www.daniweb.com/forums/thread49.html
and also to make gtalk bot through Imified but this site doesn't work anymore. Besides it doesn't give much options. Can anyone provide me good tutorial for how to make gtalk bot from scratch...

Find process, get handle, then send it the correct messages.

It depends on what you want to do. Their servers are XMPP based. You could probably use any XMPP library in your language of choice to implement text-based messaging. Just look for an XMPP tutorial in your language of choice.
Here's one in Python, which links to a couple other Python implementations: http://xmpppy.sourceforge.net/

Google has developed extensions to the protocol for audio/video called Jingle. You can find Google's open source implementation at http://code.google.com/p/libjingle/. More info at http://code.google.com/apis/talk/libjingle/index.html. It's my understanding that this is out of date and may not even compile without some work (it's a shame Google doesn't keep this up to date). I believe there may be other open source implementations out there that might be of use if you want audio/video.