WordPress is great but each upgrade or theme change is a bit painful because all customizations have to be moved manually and as long they are direct file edits, including fixes for not quite correct theme files.
So after all at least some of the updates have to be made as WordPress Plugins.
Here we start with Google Talk Sidebar Widget Plugin (for WordPress 2.5). Google offered chatback badge to offer web chat through Jabber/XMPP compatible Google Talk instant messaging network.
User quotes:
What’s cool about it is it’s anonymous both ways. I don’t have to expose my Google-ness to random visitors on the web, and if it gets annoying I can turn it off. Also, and most likely to be actually useful, people I actually know can go to my blog, check my status, and ping me if I’m around, all without downloading a client. On their end, Google is just running a web browser session for them. They don’t even need a Google account.
Download link: wp-googletalk.zip
Permanent link: https://alax.info/blog/tag/wp-googletalk (to bookmark or revisit)
Installation is standard for plugins and after activation a new widget is available on widgets page.

Copy paste <iframe> code from Google chatback badge page into Text field and the widget is ready for use. on your website.
See also: